BA6933 Statistics Week 3 Quiz ( Chapter 7 & 8 )

 A simple random sample of 64 observations was taken from a large population. The sample mean and the standard deviation were determined to be 320 and 120 respectively. The standard error of the mean is

a. 40

b. 15

c. 1.875

d. 5

Hide Feedback

Correct

Solution

Correct Response

b

Random samples of size 17 are taken from a population that has 200 elements, a mean of 36, and a standard deviation of 8. The mean and the standard deviation of the sampling distribution of the sample means are

a. 36 and 1.86.

b. 8.7 and 1.94.

c. 36 and 8.

d. 36 and 1.94.

Hide Feedback

Correct

Solution

Correct Response

a

How many simple random samples of size 5 can be selected from a population of size 8?

a. 336

b. 56

c. 40

d. 68

Hide Feedback

Correct

Solution

Correct Response

b

A sample of 66 observations will be taken from an infinite population. The population proportion equals 0.12. The probability that the sample proportion will be less than 0.1768 is

a. 0.0778

b. 0.9222

c. 0.0568

d. 0.4222

Hide Feedback

Correct

Solution

Correct Response

b

The following information was collected from a simple random sample of a population.

16

19

18

17

20

18

The point estimate of the mean of the population is

a. 16

b. 108

c. 19.6

d. 18.0

Hide Feedback

Correct

Solution

Correct Response

d

Random samples of size 100 are taken from an infinite population whose population proportion is 0.2. The mean and standard deviation of the sample proportion are

a. 0.2 and 0.2

b. 20 and .04

c. 0.2 and .04

d. 20 and 0.2

Hide Feedback

Correct

Solution

Correct Response

c

The sample statistic, such as x̄, s, or p̄, that provides the point estimate of the population parameter is known as

a. a population parameter.

b. a point estimator.

c. a parameter.

d. a population statistic.

Hide Feedback

Correct

Solution

Correct Response

b

The standard deviation of p̄ is referred to as the

a. deviated proportion.

b. sample mean proportion.

c. standard error of the proportion.

d. standard proportion.

Hide Feedback

Correct

Solution

Correct Response

c

A sample of 25 observations is taken from an infinite population. The sampling distribution of p̄ is

a. not normal since n < 30

b. approximately normal if np > 30 and n(1-P) > 30

c. approximately normal because p̄ is always normally distributed

d. approximately normal if np ≥ 5 and n(1-P) ≥ 5

Hide Feedback

Correct

Solution

Correct Response

d

In point estimation

a. the mean of the population equals the mean of the sample.

b. data from the sample is used to estimate the sample statistic.

c. data from the sample is used to estimate the population parameter.

d. data from the population is used to estimate the population parameter.

Hide Feedback

Incorrect

Solution

Correct Response

c

In a sample of 400 voters, 360 indicated they favor the incumbent governor. The 95% confidence interval of voters not favoring the incumbent is

a. .871 to .929.

b. .071 to .129.

c. .765 to .835.

d. .120 to .280.

Hide Feedback

Correct

Solution

Correct Response

b

When constructing a confidence interval for the population mean using the standard deviation of the sample, the degrees of freedom for the t distribution equals

a. n + 1.

b. 2n.

c. n.

d. n - 1.

Hide Feedback

Correct

Solution

Correct Response

d

To compute the necessary sample size for an interval estimate of a population mean, all of the following procedures are recommended when σ is unknown except

a. use the estimated σ from a previous study.

b. use the sample standard deviation from a preliminary sample.

c. use judgment or a best guess.

d. use .5 as an estimate.

Hide Feedback

Correct

Solution

Correct Response

d

If we want to provide a 95% confidence interval for the mean of a population, the confidence coefficient will be

a. 1.645.

b. .95.

c. .485.

d. 1.96.

Hide Feedback

Correct

Solution

Correct Response

b

A 95% confidence interval for a population mean is determined to be 100 to 120. For the same data, if the confidence coefficient is reduced to .90, the confidence interval for μ

a. becomes 100.1 to 120.1.

b. becomes wider.

c. does not change.

d. becomes narrower.

Hide Feedback

Correct

Solution

Correct Response

d

A random sample of 30 varieties of cereal was selected. The average number of calories per serving for these cereals is  = 120. Assuming that σ = 10, find a 95% confidence interval for the mean number of calories, μ, in a serving of cereal.

a. 117.00 to 123.00

b. 116.42 to 123.58

c. 115.30 to 124.70

d. 118.00 to 122.00

Hide Feedback

Correct

Solution

Correct Response

b

We are interested in conducting a study in order to determine the percentage of voters in a city who would vote for the incumbent mayor. What is the minimum sample size needed to estimate the population proportion with a margin of error not exceeding 4% at 95% confidence?

a. 600

b. 601

c. 625

d. 626

Hide Feedback

Correct

Solution

Correct Response

b

A machine that produces a major part for an airplane engine is monitored closely. In the past, 10% of the parts produced would be defective. With a .95 probability, the sample size that needs to be taken if the desired margin of error is .04 or less is

a. 111.

b. 216.

c. 110.

d. 217.

Hide Feedback

Correct

Solution

Correct Response

d

We can use the normal distribution to make confidence interval estimates for the population proportion, p, when

a. both np ≥ 5 and n(1 - p) ≥ 5.

b. n(1 - p) ≥ 5.

c. p has a normal distribution.

d. np ≥ 5.

Hide Feedback

Correct

Solution

Correct Response

a

The t distribution should be used whenever

a. the sample standard deviation is used to estimate the population standard deviation.

b. the population standard deviation is known.

c. the population is not normally distributed.

d. the sample size is less than 30.

Hide Feedback

Correct

Solution

Correct Response

a

A population has a mean of 53 and a standard deviation of 21. A sample of 49 observations will be taken. The probability that the sample mean will be greater than 57.95 is

a. .0495

b. .9505

c. .4505

d. 0

Hide Feedback

Correct

Solution

Correct Response

a

Whenever the population has a normal probability distribution, the sampling distribution of x̄ is a normal probability distribution for

a. any sample size.

b. small sample sizes.

c. large sample sizes.

d. samples of size thirty or greater.

Hide Feedback

Correct

Solution

Correct Response

a

A simple random sample of 64 observations was taken from a large population. The sample mean and the standard deviation were determined to be 320 and 120 respectively. The standard error of the mean is

a. 15

b. 40

c. 1.875

d. 5

Hide Feedback

Correct

Solution

Correct Response

a

A population has a mean of 84 and a standard deviation of 12. A sample of 36 observations will be taken. The probability that the sample mean will be between 80.54 and 88.9 is

a. 0.9511

b. 0.7200

c. 8.3600

d. 0.0347

Hide Feedback

Correct

Solution

Correct Response

a

The population being studied is usually considered ______ if it involves an ongoing process that makes listing or counting every element in the population impossible.

a. infinite

b. finite

c. symmetric

d. skewed

Hide Feedback

Correct

Solution

Correct Response

a

Which of the following is an example of nonprobabilistic sampling?

a. Stratified simple random sampling

b. Judgment sampling

c. Cluster sampling

d. Simple random sampling

Hide Feedback

Correct

Solution

Correct Response

b

In a local university, 40% of the students live in the dormitories. A random sample of 80 students is selected for a particular study. The standard deviation of p̄, known as the standard error of the proportion is approximately

a. 5.477

b. 0.05477

c. 54.77

d. 0.5477

Hide Feedback

Correct

Solution

Correct Response

b

Four hundred people were asked whether gun laws should be more stringent. Three hundred said "yes," and 100 said "no". The point estimate of the proportion in the population who will respond "no" is

a. 75

b. 0.50

c. 0.25

d. 0.75

Hide Feedback

Correct

Solution

Correct Response

c

A wildlife management organization is interested in estimating the number of moose in a particular region. Organization employees divide the region into 10 sections and randomly select four sections to survey the number of moose present. What sampling method is being used?

a. Systematic sampling

b. Stratified random sampling

c. Cluster sampling

d. Judgment sampling

Hide Feedback

Correct

Solution

Correct Response

c

A population of size 1,000 has a proportion of 0.5. Therefore, the proportion and the standard deviation of the sample proportion for samples of size 100 are

a. 500 and 0.050

b. 0.5 and 0.047

c. 0.5 and 0.050

d. 500 and 0.047

Hide Feedback

Correct

Solution

Correct Response

b

The sample size needed to provide a margin of error of 2 or less with a .95 probability when the population standard deviation equals 11 is

a. 117.

b. 11.

c. 10.

d. 116.

Hide Feedback

Correct

Solution

Correct Response

a

When s is used to estimate σ, the margin of error is computed by using the

a. t distribution.

b. normal distribution.

c. mean of the population.

d. mean of the sample.

Hide Feedback

Correct

Solution

Correct Response

a

The manager of a department store wants to determine the proportion of customers who use the store's credit card when making a purchase. What sample size should he select so that at 96% confidence the error will not be more than 10%?

a. 106

b. 76

c. 1

d. There is not enough information given to determine the sample size.

Hide Feedback

Incorrect

Solution

Correct Response

a

In an interval estimation for a proportion of a population, the value of z at 99.2% confidence is

a. 2.41.

b. 2.65.

c. 1.96.

d. 1.645.

Hide Feedback

Correct

Solution

Correct Response

b

What is the t value for  and 15 degrees of freedom?

a. 2.145

b. 0.691

c. 2.120

d. 2.131

Hide Feedback

Correct

Solution

Correct Response

d

In a sample of 400 voters, 360 indicated they favor the incumbent governor. The 95% confidence interval of voters not favoring the incumbent is

a. .120 to .280.

b. .871 to .929.

c. .071 to .129.

d. .765 to .835.

Hide Feedback

Correct

Solution

Correct Response

c

An estimate of a population parameter that provides an interval of values believed to contain the value of the parameter is known as the

a. interval estimate.

b. confidence level.

c. margin of error.

d. point estimate.

Hide Feedback

Correct

Solution

Correct Response

a

From a population that is normally distributed, a sample of 25 elements is selected and the standard deviation of the sample is computed. For the interval estimation of μ, the proper distribution to use is the

a. t distribution with 24 degrees of freedom.

b. t distribution with 25 degrees of freedom.

c. t distribution with 26 degrees of freedom.

d. normal distribution.

Hide Feedback

Correct

Solution

Correct Response

a

A sample of 75 information systems managers had an average hourly income of $40.75 with a standard deviation of $7.00. The standard error of the mean is

a. 80.83.

b. 7.0.

c. 1.611.

d. .8083.

Hide Feedback

Incorrect

Solution

Correct Response

d

The t distribution should be used whenever

a. the population is not normally distributed.

b. the sample size is less than 30.

c. the sample standard deviation is used to estimate the population standard deviation.

d. the population standard deviation is known.

Hide Feedback

Correct

Solution

Correct Response

c

Which of the following best describes the form of the sampling distribution of the sample proportion?

a. When standardized, it is the t distribution.

b. When standardized, it is exactly the standard normal distribution.

c. It is approximately normal as long as n ≥ 30.

d. It is approximately normal as long as np ≥ 5 and n(1 - p) ≥ 5.

Hide Feedback

Correct

Solution

Correct Response

d

A sample of 66 observations will be taken from an infinite population. The population proportion equals 0.12. The probability that the sample proportion will be less than 0.1768 is

a. 0.0778

b. 0.4222

c. 0.9222

d. 0.0568

Hide Feedback

Correct

Solution

Correct Response

c

A wildlife management organization is interested in estimating the number of moose in a particular region. Organization employees divide the region into 10 sections and randomly select four sections to survey the number of moose present. What sampling method is being used?

a. Systematic sampling

b. Cluster sampling

c. Stratified random sampling

d. Judgment sampling

Hide Feedback

Correct

Solution

Correct Response

b

It is impossible to construct a frame for a(n)

a. finite population.

b. infinite population.

c. target population.

d. defined population.

Hide Feedback

Correct

Solution

Correct Response

b

A population has a mean of 84 and a standard deviation of 12. A sample of 36 observations will be taken. The probability that the sample mean will be between 80.54 and 88.9 is

a. 0.9511

b. 8.3600

c. 0.0347

d. 0.7200

Hide Feedback

Correct

Solution

Correct Response

a

A random sample of 150 people was taken from a very large population. Ninety of the people in the sample were female. The standard error of the proportion is

a. 0.0016

b. 0.1600

c. 0.0400

d. 0.2400

Hide Feedback

Correct

Solution

Correct Response

c

A population has a mean of 300 and a standard deviation of 18. A sample of 144 observations will be taken. The probability that the sample mean will be between 297 to 303 is

a. 0.9332.

b. 0.0668.

c. 0.4332.

d. 0.9544.

Hide Feedback

Correct

Solution

Correct Response

d

As a rule of thumb, the sampling distribution of the sample proportions can be approximated by a normal probability distribution whenever

a. np ≥5, n ≥30.

b. n ≥ 30 and (1 - p) = 0.5.

c. np ≥5 and n(1-p) ≥5.

d. None of these alternatives are correct.

Hide Feedback

Correct

Solution

Correct Response

c

Random samples of size 36 are taken from an infinite population whose mean and standard deviation are 20 and 15, respectively. The distribution of the population is unknown. The mean and the standard error of the mean are

a. 20 and 15

b. 20 and 0.417

c. 36 and 15

d. 20 and 2.5

Hide Feedback

Correct

Solution

Correct Response

d

The number of simple random samples of size 20 that can be selected from a finite population of size 25 is _____.

a. 53,130

b. 1

c. 120

d. 20

Hide Feedback

Correct

Solution

Correct Response

a

If we consider the simple random sampling process as an experiment, the sample mean is

a. always zero.

b. exactly equal to the population mean.

c. a random variable.

d. always smaller than the population mean.

Hide Feedback

Correct

Solution

Correct Response

c

Which of the following is an example of nonprobabilistic sampling?

a. Cluster sampling

b. Simple random sampling

c. Judgment sampling

d. Stratified simple random sampling

Hide Feedback

Correct

Solution

Correct Response

c

The sampling distribution of the sample means

a. is used as a point estimator of the population mean μ.

b. is an unbiased estimator.

c. is the probability distribution showing all possible values of the sample mean.

d. shows the distribution of all possible values of μ.

Hide Feedback

Correct

Solution

Correct Response

c

A sample of 240 is selected from a finite population of 500. If the standard deviation of the population is 44, what is the standard error of the sample mean?

a. 1.42

b. 2.84

c. 2.05

d. 4.20

Hide Feedback

Incorrect

Solution

Correct Response

b

Four hundred people were asked whether gun laws should be more stringent. Three hundred said "yes," and 100 said "no". The point estimate of the proportion in the population who will respond "yes" is

a. 0.25

b. approximately 300

c. 300

d. 0.75

Hide Feedback

Correct

Solution

Correct Response

d

In point estimation

a. data from the population is used to estimate the population parameter.

b. data from the sample is used to estimate the sample statistic.

c. the mean of the population equals the mean of the sample.

d. data from the sample is used to estimate the population parameter.

Hide Feedback

Correct

Solution

Correct Response

d

A population of size 1,000 has a proportion of 0.5. Therefore, the proportion and the standard deviation of the sample proportion for samples of size 100 are

a. 0.5 and 0.047

b. 500 and 0.047

c. 500 and 0.050

d. 0.5 and 0.050

Hide Feedback

Correct

Solution

Correct Response

a

The probability distribution of all possible values of the sample mean x̄ is

a. the sampling distribution of x̄.

b. the probability density function of x̄.

c. one, since it considers all possible values of the sample mean.

d. the grand mean, since it considers all possible values of the sample mean.

Hide Feedback

Correct

Solution

Correct Response

a

The population being studied is usually considered ______ if it involves an ongoing process that makes listing or counting every element in the population impossible.

a. symmetric

b. skewed

c. finite

d. infinite

Hide Feedback

Correct

Solution

Correct Response

d

A population of size 320 has a proportion equal to .60 for the characteristic of interest. What are the mean and the standard deviation, respectively, of the sample proportion for samples of size 12?

a. .60 and .02

b. 320 and .02

c. 192 and 45

d. .60 and .14

Hide Feedback

Correct

Solution

Correct Response

d

From a population that is not normally distributed and whose standard deviation is not known, a sample of 6 items is selected to develop an interval estimate for the mean of the population (μ).

a. The normal distribution can be used.

b. The sample size must be increased.

c. The t distribution with 5 degrees of freedom must be used.

d. The t distribution with 6 degrees of freedom must be used.

Hide Feedback

Correct

Solution

Correct Response

b

If we want to provide a 95% confidence interval for the mean of a population, the confidence coefficient will be

a. .485.

b. 1.96.

c. .95.

d. 1.645.

Hide Feedback

Correct

Solution

Correct Response

c

When s is used to estimate σ, the margin of error is computed by using the

a. t distribution.

b. normal distribution.

c. mean of the sample.

d. mean of the population.

Hide Feedback

Correct

Solution

Correct Response

a

The probability that the interval estimation procedure will generate an interval that does not contain the actual value of the population parameter being estimated is the

a. margin of error.

b. proportion estimate.

c. same as α.

d. confidence coefficient.

Hide Feedback

Incorrect

Solution

Correct Response

c

A population has a standard deviation of 50. A random sample of 100 items from this population is selected. The sample mean is determined to be 600. At 95% confidence, the margin of error is

a. 8.225.

b. 9.92.

c. 9.8.

d. 8.3.

Hide Feedback

Correct

Solution

Correct Response

c

A sample of 75 information systems managers had an average hourly income of $40.75 with a standard deviation of $7.00. If we want to determine a 95% confidence interval for the average hourly income of the population, the value of t is

a. 1.28.

b. 1.645.

c. 1.96.

d. 1.993.

Hide Feedback

Correct

Solution

Correct Response

d

A sample of 75 information systems managers had an average hourly income of $40.75 with a standard deviation of $7.00. The standard error of the mean is

a. 7.0.

b. 80.83.

c. 1.611.

d. .8083.

Hide Feedback

Correct

Solution

Correct Response

d

To compute the minimum sample size for an interval estimate of μ, we must first determine all of the following except

a. population standard deviation.

b. degrees of freedom.

c. confidence level.

d. desired margin of error.

Hide Feedback

Correct

Solution

Correct Response

b

A sample of 75 information systems managers had an average hourly income of $40.75 with a standard deviation of $7.00. The value of the margin of error at 95% confidence is

a. 7.00.

b. .81.

c. 1.61.

d. 80.83.

Hide Feedback

Correct

Solution

Correct Response

c

A sample of 75 information systems managers had an average hourly income of $40.75 with a standard deviation of $7.00. The 95% confidence interval for the average hourly wage (in $) of all information system managers is

a. 39.40 to 42.10.

b. 37.54 to 43.96.

c. 38.61 to 42.89.

d. 39.14 to 42.36.

Hide Feedback

Correct

Solution

Correct Response

d

The following random sample from a population whose values were normally distributed was collected.

10

8

11

11

The 95% confidence interval for μ is

a. 7.75 to 12.25.

b. 8.00 to 10.00.

c. 9.25 to 10.75.

d. 8.52 to 11.48.

Hide Feedback

Correct

Solution

Correct Response

a

To compute the necessary sample size for an interval estimate of a population mean, all of the following procedures are recommended when σ is unknown except

a. use the sample standard deviation from a preliminary sample.

b. use judgment or a best guess.

c. use .5 as an estimate.

d. use the estimated σ from a previous study.

Hide Feedback

Correct

Solution

Correct Response

c

A random sample of 64 students at a university showed an average age of 25 years and a sample standard deviation of 2 years. The 98% confidence interval for the true average age of all students in the university is

a. 24.4 to 25.6.

b. 23.0 to 27.0.

c. 20.0 to 30.0.

d. 20.5 to 29.5.

Hide Feedback

Correct

Solution

Correct Response

a

Using an α = .04, a confidence interval for a population proportion is determined to be .65 to .75. For the same data, if α is decreased, the confidence interval for the population proportion

a. remains the same.

b. uses a zero margin of error.

c. becomes narrower.

d. becomes wider.

Hide Feedback

Correct

Solution

Correct Response

d

The degrees of freedom associated with a t distribution are a function of the

a. area in the upper tail.

b. confidence coefficient.

c. sample size.

d. sample standard deviation.

Hide Feedback

Correct

Solution

Correct Response

c

Using α = 0.05, a confidence interval for a population proportion is determined to be 0.15 to 0.35. If the level of significance is increased, the interval for the population proportion

a. becomes narrower.

b. becomes wider.

c. does not change.

d. Not enough information is provided to answer this question.

Hide Feedback

Correct

Solution

Correct Response

a

The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the

a. standard deviation.

b. degrees of freedom.

c. finite correction factor.

d. sample size.

Hide Feedback

Correct

Solution

Correct Response

b

A random sample of 64 SAT scores of students applying for merit scholarships showed an average of 1400 with a standard deviation of 240. The t value needed to develop the 95% confidence interval for the population mean SAT score is

a. 1.96.

b. 1.645.

c. 1.998.

d. 1.28.

Hide Feedback

Incorrect

Solution

Correct Response

c

Which of the following must be decided by the researcher when computing the minimum sample size for an interval estimate of μ or p?

a. Mean

b. Margin of error

c. Degrees of freedom

d. Standard deviation

Hide Feedback

Correct

Solution

Correct Response

b

We can use the normal distribution to make confidence interval estimates for the population proportion, p, when

a. both np ≥ 5 and n(1 - p) ≥ 5.

b. p has a normal distribution.

c. np ≥ 5.

d. n(1 - p) ≥ 5.

Hide Feedback

Incorrect

Solution

Correct Response

a

A sample statistic is an unbiased estimator of the population parameter when

a. the standard deviation of the sampling distribution is less than 5.

b. the expected value of the sample statistic is equal to the value of the population parameter.

c. the data was used to estimate a population mean.

d. the mean of the sampling distribution has a z-score of zero.

Hide Feedback

Correct

Solution

Correct Response

b

The expected value of equals the mean of the population from which the sample is drawn

a. only if the sample size is 30 or greater.

b. for any sample size.

c. only if the sample size is 100 or greater.

d. only if the sample size is 50 or greater.

Hide Feedback

Correct

Solution

Correct Response

b

A probability sampling method in which we randomly select one of the first k elements and then select every k th element thereafter is

a. systematic sampling.

b. cluster sampling.

c. convenience sampling.

d. stratified random sampling.

Hide Feedback

Correct

Solution

Correct Response

a

Which of the following is(are) point estimator(s)?

a. μ

b. σ

c. α

d. s

Hide Feedback

Correct

Solution

Correct Response

d

A population has a mean of 84 and a standard deviation of 12. A sample of 36 observations will be taken. The probability that the sample mean will be between 80.54 and 88.9 is

a. 8.3600

b. 0.0347

c. 0.9511

d. 0.7200

Hide Feedback

Correct

Solution

Correct Response

c

A simple random sample of 5 observations from a population containing 400 elements was taken, and the following values were obtained.

12

18

19

20

21

A point estimate of the mean is

a. 10

b. 400

c. 18

d. 20

Hide Feedback

Correct

Solution

Correct Response

c

Suppose candidate A for a town council seat receives 43% of the votes in an election. As voters leave the polls, they are asked who they voted for. What is the probability that less than 40% of the 80 voters surveyed indicate they voted for candidate A? Assume an infinite population.

a. .1368

b. .8632

c. .2939

d. .7061

Hide Feedback

Correct

Solution

Correct Response

c

Suppose the salaries of university professors are approximately normally distributed with a mean of $65,000 and a standard deviation of $7,000. If a random sample of size 25 is taken and the mean is calculated, what is the probability that the mean value will be between $62,500 and $64,000?

a. .2005

b. .1465

c. .0827

d. .0371

Hide Feedback

Correct

Solution

Correct Response

a

In a local university, 40% of the students live in the dormitories. A random sample of 80 students is selected for a particular study. The standard deviation of p̄, known as the standard error of the proportion is approximately

a. 0.5477

b. 5.477

c. 54.77

d. 0.05477

Hide Feedback

Correct

Solution

Correct Response

d

A probability distribution of all possible values of a sample statistic is known as

a. a parameter.

b. a sampling distribution.

c. a sample statistic.

d. simple random sampling.

Hide Feedback

Correct

Solution

Correct Response

b

A population consists of 8 items. The number of different simple random samples of size 3 that can be selected from this population is

a. 56

b. 128

c. 24

d. 512

Hide Feedback

Correct

Solution

Correct Response

a

The following information was collected from a simple random sample of a population.

16

19

18

17

20

18

The point estimate of the population standard deviation is

a. 1.667

b. 1.414

c. 2.000

d. 1.291

Hide Feedback

Correct

Solution

Correct Response

b

In point estimation

a. data from the population is used to estimate the population parameter.

b. the mean of the population equals the mean of the sample.

c. data from the sample is used to estimate the sample statistic.

d. data from the sample is used to estimate the population parameter.

Hide Feedback

Correct

Solution

Correct Response

d

A wildlife management organization is interested in estimating the number of moose in a particular region. Organization employees divide the region into 10 sections and randomly select four sections to survey the number of moose present. What sampling method is being used?

a. Stratified random sampling

b. Systematic sampling

c. Judgment sampling

d. Cluster sampling

Hide Feedback

Correct

Solution

Correct Response

d

The number of simple random samples of size 20 that can be selected from a finite population of size 25 is _____.

a. 120

b. 1

c. 53,130

d. 20

Hide Feedback

Correct

Solution

Correct Response

c

The purpose of statistical inference is to provide information about the

a. mean of the sample based upon the mean of the population.

b. population based upon information contained in the sample.

c. population based upon information contained in the population.

d. sample based upon information contained in the population.

Hide Feedback

Correct

Solution

Correct Response

b

Cluster sampling is

a. a nonprobability sampling method.

b. the same as convenience sampling.

c. a systematic sampling method.

d. a probability sampling method.

Hide Feedback

Correct

Solution

Correct Response

d

A single numerical value used as an estimate of a population parameter is known as

a. a parameter.

b. a point estimate.

c. a mean estimator.

d. a population parameter.

Hide Feedback

Correct

Solution

Correct Response

b

If we select simple random samples of size 2 from the given data, what is the probability of any of the five employees being selected first?

a. .50

b. .40

c. .10

d. .20

Hide Feedback

Correct

Solution

Correct Response

d

The extent of the sampling error might be affected by all of the following factors except

a. the variability of the population.

b. the expected value of the sample statistic.

c. the sample size.

d. the sampling method used.

Hide Feedback

Correct

Solution

Correct Response

b

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. If the sample mean is 9 hours, then the 95% confidence interval is

a. 7.36 to 10.64 hours.

b. 7.04 to 10.96 hours.

c. 7.80 to 10.20 hours.

d. 8.61 to 9.39 hours.

Hide Feedback

Correct

Solution

Correct Response

d

A random sample of 64 students at a university showed an average age of 25 years and a sample standard deviation of 2 years. The 98% confidence interval for the true average age of all students in the university is

a. 23.0 to 27.0.

b. 20.5 to 29.5.

c. 20.0 to 30.0.

d. 24.4 to 25.6.

Hide Feedback

Correct

Solution

Correct Response

d

A random sample of 144 observations has a mean of 20, a median of 21, and a mode of 22. The population standard deviation is known to equal 4.8. The 95.44% confidence interval for the population mean is

a. 15.2 to 24.8.

b. 19.20 to 20.80.

c. 21.2 to 22.8.

d. 19.216 to 20.784.

Hide Feedback

Correct

Solution

Correct Response

b

In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determined. Assume a population standard deviation of 450 kilowatt-hours. If the sample mean is 1858 kWh, the 95% confidence interval estimate of the population mean is

a. 1776 to 1940 kWh.

b. 1729 to 1987 kWh.

c. 1758 to 1958 kWh.

d. 1760 to 1956 kWh.

Hide Feedback

Correct

Solution

Correct Response

d

A 95% confidence interval and a 99% confidence interval are computed from the same set of data. Which of the following statements is correct?

a. The intervals have the same width.

b. You need to know the sample size, n, and the standard deviation to determine which interval is wider.

c. The 99% confidence interval is wider.

d. The 95% confidence interval is wider.

Hide Feedback

Correct

Solution

Correct Response

c

As the number of degrees of freedom for a t distribution increases, the difference between the t distribution and the standard normal distribution

a. fluctuates.

b. stays the same.

c. becomes smaller.

d. becomes larger.

Hide Feedback

Correct

Solution

Correct Response

c

A random sample of 64 SAT scores of students applying for merit scholarships showed an average of 1400 with a standard deviation of 240. The 95% confidence interval for the population mean SAT score is

a. 1340.06 to 1459.94.

b. 1320.32 to 1479.68.

c. 1341.20 to 1458.80.

d. 1349.93 to 1450.07.

Hide Feedback

Correct

Solution

Correct Response

a

Using α = 0.05, a confidence interval for a population proportion is determined to be 0.15 to 0.35. If the level of significance is increased, the interval for the population proportion

a. becomes narrower.

b. becomes wider.

c. does not change.

d. Not enough information is provided to answer this question.

Hide Feedback

Correct

Solution

Correct Response

a

Which of the following is not required when computing the sample size for an interval estimate of the population mean?

a. Population mean

b.

c. Margin of error the researcher is willing to accept

d. Population standard deviation

Hide Feedback

Correct

Solution

Correct Response

a

A random sample of 15 employees was selected. The average age in the sample was 31 years with a variance of 49 years. Assuming ages are normally distributed, the 98% confidence interval for the population average age is _____.

a. 25.62 to 36.38

b. 27.82 to 34.18

c. 11.54 to 18.46

d. 26.26 to 35.74

Hide Feedback

Incorrect

Solution

Correct Response

d

A population has a standard deviation of 50. A random sample of 100 items from this population is selected. The sample mean is determined to be 600. At 95% confidence, the margin of error is

a. 8.225.

b. 9.92.

c. 9.8.

d. 8.3.

Hide Feedback

Correct

Solution

Correct Response

c

The t distribution should be used whenever

a. the sample size is less than 30.

b. the population is not normally distributed.

c. the sample standard deviation is used to estimate the population standard deviation.

d. the population standard deviation is known.

Hide Feedback

Correct

Solution

Correct Response

c

We are interested in conducting a study to determine the percentage of voters of a state would vote for the incumbent governor. What is the minimum sample size needed to estimate the population proportion with a margin of error of .05 or less at 95% confidence?

a. 200.

b. 385.

c. 58.

d. 100.

Hide Feedback

Correct

Solution

Correct Response

b

If we change a 95% confidence interval estimate to a 99% confidence interval estimate, we can expect the

a. width of the confidence interval to decrease.

b. width of the confidence interval to remain the same.

c. width of the confidence interval to increase.

d. sample size to increase.

Hide Feedback

Correct

Solution

Correct Response

c

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. With a .95 probability, the margin of error is approximately

a. .39.

b. 1.64.

c. 1.96.

d. .20.

Hide Feedback

Correct

Solution

Correct Response

a

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. If the sample mean is 9 hours, then the 95% confidence interval is

a. 7.36 to 10.64 hours.

b. 7.04 to 10.96 hours.

c. 7.80 to 10.20 hours.

d. 8.61 to 9.39 hours.

Hide Feedback

Correct

Solution

Correct Response

d

As the degrees of freedom increase, the t distribution approaches the

a. exponential distribution.

b. p distribution.

c. normal distribution.

d. uniform distribution.

Hide Feedback

Correct

Solution

Correct Response

c

In which of the following situations should the t distribution be used?

a. When the sample standard deviation is used to estimate the population standard deviation

b. When the sample size is less than 30

c. When the population is not normally distributed

d. Only when the population mean is 0

Hide Feedback

Correct

Solution

Correct Response

a

The following random sample from a population whose values were normally distributed was collected.

10

8

11

11

The 95% confidence interval for μ is

a. 7.75 to 12.25.

b. 9.25 to 10.75.

c. 8.52 to 11.48.

d. 8.00 to 10.00.

Hide Feedback

Correct

Solution

Correct Response

a

It is known that the population variance equals 484. With a .95 probability, the sample size that needs to be taken if the desired margin of error is 5 or less is

a. 189.

b. 190.

c. 74.

d. 75.

Hide Feedback

Correct

Solution

Correct Response

d

The sampling error is the

a. same as the standard error of the mean.

b. error caused by selecting a bad sample.

c. difference between the value of the sample mean and the value of the population mean.

d. standard deviation multiplied by the sample size.

Hide Feedback

Correct

Solution

Correct Response

c

A probability distribution of all possible values of a sample statistic is known as

a. a sampling distribution.

b. a sample statistic.

c. a parameter.

d. simple random sampling.

Hide Feedback

Correct

Solution

Correct Response

a

A simple random sample of 100 observations was taken from a large population. The sample mean and the standard deviation were determined to be 80 and 12 respectively. The standard error of the mean is

a. 8.00

b. 0.80

c. 0.12

d. 1.20

Hide Feedback

Correct

Solution

Correct Response

d

Doubling the size of the sample will

a. reduce the standard error of the mean to approximately 70% of its current value.

b. have no effect on the standard error of the mean.

c. reduce the standard error of the mean to one-half its current value.

d. double the standard error of the mean.

Hide Feedback

Correct

Solution

Correct Response

a

The standard error of the proportion will become larger as

a. n increases.

b. p approaches .5.

c. p approaches 1.

d. p approaches 0.

Hide Feedback

Correct

Solution

Correct Response

b

In a local university, 40% of the students live in the dormitories. A random sample of 80 students is selected for a particular study. The standard deviation of p̄, known as the standard error of the proportion is approximately

a. 5.477

b. 0.5477

c. 54.77

d. 0.05477

Hide Feedback

Correct

Solution

Correct Response

d

The closer the sample mean is to the population mean,

a. the smaller the sampling error.

b. the larger the sampling error.

c. the sampling error equals 1.

d. None of these alternatives are correct.

Hide Feedback

Correct

Solution

Correct Response

a

The probability distribution of all possible values of the sample mean x̄ is

a. the grand mean, since it considers all possible values of the sample mean.

b. the sampling distribution of x̄.

c. one, since it considers all possible values of the sample mean.

d. the probability density function of x̄.

Hide Feedback

Correct

Solution

Correct Response

b

From a population of 500 elements, a sample of 225 elements is selected. It is known that the variance of the population is 900. The standard error of the mean is approximately

a. 2

b. 30

c. 1.1022

d. 1.4847

Hide Feedback

Correct

Solution

Correct Response

d

It is impossible to construct a frame for a(n)

a. finite population.

b. infinite population.

c. target population.

d. defined population.

Hide Feedback

Correct

Solution

Correct Response

b

From a population of 200 elements, a sample of 49 elements is selected. It is determined that the sample mean is 56 and the sample standard deviation is 14. The standard error of the mean is

a. 3

b. greater than 2

c. 2

d. less than 2

Hide Feedback

Correct

Solution

Correct Response

d

A sample of 24 observations is taken from a population that has 150 elements. The sampling distribution of x̄ is

a. approximately normal because of the central limit theorem.

b. normal if the population is normally distributed.

c. approximately normal because x̄ is always approximately normally distributed.

d. approximately normal because the sample size is large in comparison to the population size.

Hide Feedback

Correct

Solution

Correct Response

b

A population of size 1,000 has a proportion of 0.5. Therefore, the proportion and the standard deviation of the sample proportion for samples of size 100 are

a. 0.5 and 0.050

b. 0.5 and 0.047

c. 500 and 0.047

d. 500 and 0.050

Hide Feedback

Correct

Solution

Correct Response

b

The following information was collected from a simple random sample of a population.

16

19

18

17

20

18

The point estimate of the population standard deviation is

a. 1.667

b. 1.291

c. 1.414

d. 2.000

Hide Feedback

Correct

Solution

Correct Response

c

For a population with any distribution, the form of the sampling distribution of the sample mean is

a. sometimes normal for all sample sizes.

b. sometimes normal for large sample sizes.

c. always normal for all sample sizes.

d. always normal for large sample sizes.

Hide Feedback

Correct

Solution

Correct Response

d

Which of the following is an example of nonprobabilistic sampling?

a. Judgment sampling

b. Stratified simple random sampling

c. Cluster sampling

d. Simple random sampling

Hide Feedback

Correct

Solution

Correct Response

a

As the sample size increases, the

a. population mean increases.

b. standard deviation of the population decreases.

c. standard error of the mean increases.

d. standard error of the mean decreases.

Hide Feedback

Correct

Solution

Correct Response

d

The purpose of statistical inference is to provide information about the

a. population based upon information contained in the population.

b. sample based upon information contained in the population.

c. mean of the sample based upon the mean of the population.

d. population based upon information contained in the sample.

Hide Feedback

Correct

Solution

Correct Response

d

A random sample of 121 bottles of cologne showed an average content of 4 ounces. It is known that the standard deviation of the contents (i.e., of the population) is 0.22 ounces. In this problem the 0.22 is

a. the standard error of the mean.

b. a statistic.

c. a parameter.

d. the average content of colognes in the long run.

Hide Feedback

Correct

Solution

Correct Response

c

A population has a mean of 180 and a standard deviation of 24. A sample of 64 observations will be taken. The probability that the sample mean will be between 183 and 186 is

a. 0.8185

b. 0.3413

c. 0.4772

d. 0.1359

Hide Feedback

Correct

Solution

Correct Response

d

The following information was collected from a simple random sample of a population.

16

19

18

17

20

18

The point estimate of the population standard deviation is

a. 1.291

b. 1.667

c. 2.000

d. 1.414

Hide Feedback

Correct

Solution

Correct Response

d

Suppose candidate A for a town council seat receives 43% of the votes in an election. As voters leave the polls, they are asked who they voted for. What is the probability that less than 40% of the 80 voters surveyed indicate they voted for candidate A? Assume an infinite population.

a. .8632

b. .2939

c. .7061

d. .1368

Hide Feedback

Correct

Solution

Correct Response

b

A population has a mean of 80 and a standard deviation of 7. A sample of 49 observations will be taken. The probability that the sample mean will be larger than 82 is

a. 0.9772

b. 0.0228

c. 0.4772

d. 0.5228

Hide Feedback

Correct

Solution

Correct Response

b

Cluster sampling is

a. a probability sampling method.

b. a nonprobability sampling method.

c. a systematic sampling method.

d. the same as convenience sampling.

Hide Feedback

Correct

Solution

Correct Response

a

As the sample size increases, the

a. standard deviation of the population decreases.

b. standard error of the mean increases.

c. standard error of the mean decreases.

d. population mean increases.

Hide Feedback

Correct

Solution

Correct Response

c

The population being studied is usually considered ______ if it involves an ongoing process that makes listing or counting every element in the population impossible.

a. infinite

b. symmetric

c. skewed

d. finite

Hide Feedback

Correct

Solution

Correct Response

a

A finite population correction factor is needed in computing the standard deviation of the sampling distribution of sample means

a. whenever the sample size is more than 5% of the population size.

b. whenever the population is infinite.

c. irrespective of the size of the sample.

d. whenever the sample size is less than 5% of the population size.

Hide Feedback

Correct

Solution

Correct Response

a

A simple random sample of size n from an infinite population of size N is to be selected. Each possible sample should have

a. the same probability of being selected

b. a probability of 1/n of being selected

c. a probability of 1/N of being selected

d. a probability of N/n of being selected

Hide Feedback

Correct

Solution

Correct Response

a

A random sample of 121 bottles of cologne showed an average content of 4 ounces. It is known that the standard deviation of the contents (i.e., of the population) is 0.22 ounces. In this problem the 0.22 is

a. a parameter.

b. the standard error of the mean.

c. the average content of colognes in the long run.

d. a statistic.

Hide Feedback

Correct

Solution

Correct Response

a

A population of size 320 has a proportion equal to .60 for the characteristic of interest. What are the mean and the standard deviation, respectively, of the sample proportion for samples of size 12?

a. .60 and .02

b. .60 and .14

c. 320 and .02

d. 192 and 45

Hide Feedback

Correct

Solution

Correct Response

b

A finite population correction factor is needed in computing the standard deviation of the sampling distribution of sample means

a. whenever the sample size is more than 5% of the population size.

b. whenever the sample size is less than 5% of the population size.

c. irrespective of the size of the sample.

d. whenever the population is infinite.

Hide Feedback

Correct

Solution

Correct Response

a

A simple random sample of size n from an infinite population of size N is to be selected. Each possible sample should have

a. a probability of 1/n of being selected

b. the same probability of being selected

c. a probability of 1/N of being selected

d. a probability of N/n of being selected

Hide Feedback

Correct

Solution

Correct Response

b

In point estimation

a. data from the sample is used to estimate the sample statistic.

b. the mean of the population equals the mean of the sample.

c. data from the sample is used to estimate the population parameter.

d. data from the population is used to estimate the population parameter.

Hide Feedback

Correct

Solution

Correct Response

c

The sample statistic, such as x̄, s, or p̄, that provides the point estimate of the population parameter is known as

a. a parameter.

b. a point estimator.

c. a population parameter.

d. a population statistic.

Hide Feedback

Correct

Solution

Correct Response

b

All of the following are true about the standard error of the mean except

a. its value is influenced by the standard deviation of the population.

b. it measures the variability in sample means.

c. it decreases as the sample size increases.

d. it is larger than the standard deviation of the population.

Hide Feedback

Correct

Solution

Correct Response

d

Which of the following best describes the form of the sampling distribution of the sample proportion?

a. It is approximately normal as long as np ≥ 5 and n(1 - p) ≥ 5.

b. When standardized, it is the t distribution.

c. When standardized, it is exactly the standard normal distribution.

d. It is approximately normal as long as n ≥ 30.

Hide Feedback

Correct

Solution

Correct Response

a

The sampling distribution of the sample means

a. is used as a point estimator of the population mean μ.

b. shows the distribution of all possible values of μ.

c. is an unbiased estimator.

d. is the probability distribution showing all possible values of the sample mean.

Hide Feedback

Correct

Solution

Correct Response

d

A sample of 51 observations will be taken from an infinite population. The population proportion equals 0.85. The probability that the sample proportion will be between 0.9115 and 0.946 is

a. 0.8633

b. 0.0345

c. 0.6900

d. 0.0819

Hide Feedback

Correct

Solution

Correct Response

d

A sample of 66 observations will be taken from an infinite population. The population proportion equals 0.12. The probability that the sample proportion will be less than 0.1768 is

a. 0.4222

b. 0.0778

c. 0.9222

d. 0.0568

Hide Feedback

Correct

Solution

Correct Response

c

Random samples of size 81 are taken from an infinite population whose mean and standard deviation are 200 and 18, respectively. The distribution of the population is unknown. The mean and the standard error of the mean are

a. 200 and 2

b. 200 and 18

c. 81 and 18

d. 9 and 2

Hide Feedback

Correct

Solution

Correct Response

a

The following data was collected from a simple random sample of a population.

13

15

14

16

12

If the population consisted of 10 elements, how many different random samples of size 6 could be drawn from the population?

a. 362880

b. 60

c. 210

d. 3024

Hide Feedback

Correct

Solution

Correct Response

c

ampling distribution of x̄ is the

a. mean of the sample.

b. probability distribution of the sample proportion.

c. probability distribution of the sample mean.

d. mean of the population.

Hide Feedback

Correct

Solution

Correct Response

c

The standard deviation of a point estimator is called the

a. point estimator.

b. variance of estimation.

c. standard deviation.

d. standard error.

Hide Feedback

Correct

Solution

Correct Response

d

A sample of 400 observations will be taken from an infinite population. The population proportion equals 0.8. The probability that the sample proportion will be greater than 0.83 is

a. 0.9332

b. 0.4332

c. 0.5668

d. 0.0668

Hide Feedback

Correct

Solution

Correct Response

d

A population consists of 500 elements. We want to draw a simple random sample of 50 elements from this population. On the first selection, the probability of an element being selected is

a. 0.010

b. 0.100

c. 0.002

d. 0.001

Hide Feedback

Correct

Solution

Correct Response

c

A population has a mean of 84 and a standard deviation of 12. A sample of 36 observations will be taken. The probability that the sample mean will be between 80.54 and 88.9 is

a. 0.7200

b. 8.3600

c. 0.0347

d. 0.9511

Hide Feedback

Correct

Solution

Correct Response

d

Random samples of size 17 are taken from a population that has 200 elements, a mean of 36, and a standard deviation of 8. The mean and the standard deviation of the sampling distribution of the sample means are

a. 36 and 1.86.

b. 36 and 8.

c. 8.7 and 1.94.

d. 36 and 1.94.

Hide Feedback

Correct

Solution

Correct Response

a

A population has a mean of 80 and a standard deviation of 7. A sample of 49 observations will be taken. The probability that the sample mean will be larger than 82 is

a. 0.4772

b. 0.0228

c. 0.9772

d. 0.5228

Hide Feedback

Correct

Solution

Correct Response

b

A random sample of 150 people was taken from a very large population. Ninety of the people in the sample were female. The standard error of the proportion is

a. 0.0400

b. 0.2400

c. 0.0016

d. 0.1600

Hide Feedback

Correct

Solution

Correct Response

a

A wildlife management organization is interested in estimating the number of moose in a particular region. Organization employees divide the region into 10 sections and randomly select four sections to survey the number of moose present. What sampling method is being used?

a. Judgment sampling

b. Cluster sampling

c. Systematic sampling

d. Stratified random sampling

Hide Feedback

Correct

Solution

Correct Response

b

In which of the following situations should the t distribution be used?

a. When the population is not normally distributed

b. Only when the population mean is 0

c. When the sample size is less than 30

d. When the sample standard deviation is used to estimate the population standard deviation

Hide Feedback

Correct

Solution

Correct Response

d

In a sample of 400 voters, 360 indicated they favor the incumbent governor. The 95% confidence interval of voters not favoring the incumbent is

a. .871 to .929.

b. .071 to .129.

c. .120 to .280.

d. .765 to .835.

Hide Feedback

Correct

Solution

Correct Response

b

When constructing a confidence interval for the population mean using the standard deviation of the sample, the degrees of freedom for the t distribution equals

a. n + 1.

b. 2n.

c. n.

d. n - 1.

Hide Feedback

Correct

Solution

Correct Response

d

For a given confidence level and when σ is known, the margin of error in a confidence interval estimate

a. increases as the sample size increases.

b. is the same for all samples of the same size.

c. varies from sample to sample of the same size.

d. is independent of sample size.

Hide Feedback

Correct

Solution

Correct Response

b

The ability of an interval estimate to contain the value of the population parameter is described by the

a. point estimate.

b. confidence level.

c. degrees of freedom.

d. precise value of the population mean μ.

Hide Feedback

Correct

Solution

Correct Response

b

From a population that is normally distributed, a sample of 25 elements is selected and the standard deviation of the sample is computed. For the interval estimation of μ, the proper distribution to use is the

a. t distribution with 26 degrees of freedom.

b. normal distribution.

c. t distribution with 24 degrees of freedom.

d. t distribution with 25 degrees of freedom.

Hide Feedback

Correct

Solution

Correct Response

c

To compute the necessary sample size for an interval estimate of a population proportion, all of the following procedures are recommended when p is unknown except

a. use the sample proportion from a previous study.

b. use 1.0 as an estimate.

c. use judgment or a best guess.

d. use the sample proportion from a preliminary sample.

Hide Feedback

Incorrect

Solution

Correct Response

b

In interval estimation, as the sample size becomes larger, the interval estimate

a. becomes narrower.

b. remains the same, because the mean is not changing.

c. becomes wider.

d. gets closer to 1.96.

Hide Feedback

Correct

Solution

Correct Response

a

As the sample size increases, the margin of error

a. increases.

b. decreases.

c. fluctuates depending on the mean.

d. stays the same.

Hide Feedback

Correct

Solution

Correct Response

b

A university planner wants to determine the proportion of undergraduate students who plan to attend graduate school. She surveys 54 current students and finds that 27 would like to continue their education in graduate school. Which of the following is the correct 90% confidence interval estimate for the proportion of undergraduates who plan to attend graduate school?

a. 0.50 to 0.75

b. 26.727 to 27.273

c. 0.3881 to 0.6119

d. 0.3608 to 0.6392

Hide Feedback

Incorrect

Solution

Correct Response

c

The level of significance α

a. is (1 - confidence coefficient).

b. can be any positive value.

c. can be any value between -1.96 to 1.96.

d. is always a negative value.

Hide Feedback

Correct

Solution

Correct Response

a

A sample of 75 information systems managers had an average hourly income of $40.75 with a standard deviation of $7.00. If we want to determine a 95% confidence interval for the average hourly income of the population, the value of t is

a. 1.28.

b. 1.645.

c. 1.993.

d. 1.96.

Hide Feedback

Correct

Solution

Correct Response

c

The use of the normal probability distribution as an approximation of the sampling distribution of p̄ is based on the condition that both np and n(1 - p) equal or exceed

a. .05.

b. 5.

c. 30.

d. 10.

Hide Feedback

Correct

Solution

Correct Response

b

In a random sample of 144 observations, p̄ = .6. The 95% confidence interval for p is

a. .52 to .68.

b. .55 to .65.

c. .50 to .70.

d. .14 to .20.

Hide Feedback

Correct

Solution

Correct Response

a

When s is used to estimate σ, the margin of error is computed by using the

a. mean of the sample.

b. mean of the population.

c. normal distribution.

d. t distribution.

Hide Feedback

Correct

Solution

Correct Response

d

In developing an interval estimate, if the population standard deviation is unknown

a. the standard deviation is arrived at using the range.

b. it is impossible to develop the interval estimate.

c. the sample standard deviation must be used.

d. it is assumed that the population standard deviation is 1.

Hide Feedback

Correct

Solution

Correct Response

c

A random sample of 64 students at a university showed an average age of 25 years and a sample standard deviation of 2 years. The 98% confidence interval for the true average age of all students in the university is

a. 23.0 to 27.0.

b. 20.0 to 30.0.

c. 20.5 to 29.5.

d. 24.4 to 25.6.

Hide Feedback

Correct

Solution

Correct Response

d

A population has a standard deviation of 50. A random sample of 100 items from this population is selected. The sample mean is determined to be 600. At 95% confidence, the margin of error is

a. 8.3.

b. 9.8.

c. 8.225.

d. 9.92.

Hide Feedback

Correct

Solution

Correct Response

b

A random sample of 30 varieties of cereal was selected. The average number of calories per serving for these cereals is  = 120. Assuming that σ = 10, find a 95% confidence interval for the mean number of calories, μ, in a serving of cereal.

a. 115.30 to 124.70

b. 118.00 to 122.00

c. 117.00 to 123.00

d. 116.42 to 123.58

Hide Feedback

Correct

Solution

Correct Response

d

The degrees of freedom associated with a t distribution are a function of the

a. area in the upper tail.

b. confidence coefficient.

c. sample standard deviation.

d. sample size.

Hide Feedback

Correct

Solution

Correct Response

d

The t distribution should be used whenever

a. the population is not normally distributed.

b. the sample standard deviation is used to estimate the population standard deviation.

c. the sample size is less than 30.

d. the population standard deviation is known.

Hide Feedback

Correct

Solution

Correct Response

b

The manager of a retail store has taken a random sample of 50 customers. The average amount spent by these 50 customers was $110. It is known that the standard deviation of the amount spent by all customers is $10.60. If the confidence coefficient is increased from 0.95 to 0.99, the standard error of the mean will

a. double in size.

b. remain unchanged.

c. increase.

d. decrease.

Hide Feedback

Correct

Solution

Correct Response

b

The probability that the interval estimation procedure will generate an interval that does not contain the actual value of the population parameter being estimated is the

a. margin of error.

b. proportion estimate.

c. same as α.

d. confidence coefficient.

Hide Feedback

Incorrect

Solution

Correct Response

c

The margin of error in an interval estimate of the population mean is a function of all of the following except

a. variability of the population.

b. sample mean.

c. sample size.

d. α.

Hide Feedback

Correct

Solution

Correct Response

b

The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3 minutes. It is known that the standard deviation of the population of checkout times is 1 minute. The standard error of the mean equals

a. .010.

b. .100.

c. 1.000.

d. .001.

Hide Feedback

Correct

Solution

Correct Response

b

The owners of an amusement park selected a random sample of 200 days and recorded the number of park patrons with annual passes who visited the park on each selected day. They computed a 90% confidence interval for the number of patrons with annual passes who visit the park daily. How would you interpret the 90% confidence interval of (35, 51)?

a. There is a 90% chance that the population mean number of patrons with annual passes who are in the park on any given day is between 35 and 51.

b. There is a 90% chance that the sample percentage of park patrons with annual passes is contained in the interval 35 to 51.

c. The method used to calculate the confidence interval has a 90% chance of producing an interval that captures the population mean number of annual pass holders in the park on any given day.

d. Ten percent of the population of annual pass holders visit the park on any given day.

Hide Feedback

Correct

Solution

Correct Response

c

The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3 minutes. It is known that the standard deviation of the population of checkout times is 1 minute. The 95% confidence interval for the true average checkout time (in minutes) is

a. 2.804 to 3.196.

b. 2.5 to 3.5.

c. 1 to 5.

d. 1.36 to 4.64.

Hide Feedback

Correct

Solution

Correct Response

a

A random sample of 30 varieties of cereal was selected. The average number of calories per serving for these cereals is  = 120. Assuming that σ = 10, find a 95% confidence interval for the mean number of calories, μ, in a serving of cereal.

a. 116.42 to 123.58

b. 117.00 to 123.00

c. 118.00 to 122.00

d. 115.30 to 124.70

Hide Feedback

Correct

Solution

Correct Response

a

Using α = 0.05, a confidence interval for a population proportion is determined to be 0.15 to 0.35. If the level of significance is increased, the interval for the population proportion

a. becomes narrower.

b. becomes wider.

c. does not change.

d. Not enough information is provided to answer this question.

Hide Feedback

Correct

Solution

Correct Response

a

A random sample of 25 employees of a local company has been taken. A 95% confidence interval estimate for the mean systolic blood pressure for all employees of the company is 123 to 139. Which of the following statements is valid?

a. 95% of the sample of employees has a systolic blood pressure between 123 and 139.

b. If the sampling procedure were repeated many times, 95% of the sample means would be between 123 and 139.

c. 95% of the population of employees has a systolic blood pressure between 123 and 139.

d. If the sampling procedure were repeated many times, 95% of the resulting confidence intervals would contain the population mean systolic blood pressure.

Hide Feedback

Correct

Solution

Correct Response

d

The level of significance α

a. is (1 - confidence coefficient).

b. is always a negative value.

c. can be any positive value.

d. can be any value between -1.96 to 1.96.

Hide Feedback

Incorrect

Solution

Correct Response

a

In an interval estimation for a proportion of a population, the value of z at 99.2% confidence is

a. 2.65.

b. 1.645.

c. 2.41.

d. 1.96.

Hide Feedback

Correct

Solution

Correct Response

a

The use of the normal probability distribution as an approximation of the sampling distribution of p̄ is based on the condition that both np and n(1 - p) equal or exceed

a. 10.

b. 5.

c. 30.

d. .05.

Hide Feedback

Correct

Solution

Correct Response

b

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. With a .95 probability, the margin of error is approximately

a. 1.96.

b. .39.

c. 1.64.

d. .20.

Hide Feedback

Correct

Solution

Correct Response

b

The value added to and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the

a. confidence level.

b. parameter estimate.

c. margin of error.

d. planning value.

Hide Feedback

Correct

Solution

Correct Response

c

The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3 minutes. It is known that the standard deviation of the population of checkout times is 1 minute. The 95% confidence interval for the true average checkout time (in minutes) is

a. 2.804 to 3.196.

b. 1.36 to 4.64.

c. 1 to 5.

d. 2.5 to 3.5.

Hide Feedback

Correct

Solution

Correct Response

a

To compute the necessary sample size for an interval estimate of a population proportion, all of the following procedures are recommended when p is unknown except

a. use the sample proportion from a preliminary sample.

b. use the sample proportion from a previous study.

c. use judgment or a best guess.

d. use 1.0 as an estimate.

Hide Feedback

Correct

Solution

Correct Response

d

In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determined. Assume a population standard deviation of 450 kilowatt-hours. At 95% confidence, the size of the margin of error is

a. 50.00.

b. 98.00.

c. 1.96.

d. 42.00.

Hide Feedback

Incorrect

Solution

Correct Response

b

The mean of the t distribution is

a. .5.

b. problem specific.

c. 1.

d. 0.

Hide Feedback

Correct

Solution

Correct Response

d

The t distribution should be used whenever

a. the population is not normally distributed.

b. the sample size is less than 30.

c. the population standard deviation is known.

d. the sample standard deviation is used to estimate the population standard deviation.

Hide Feedback

Correct

Solution

Correct Response

d

The probability that the interval estimation procedure will generate an interval that does not contain the actual value of the population parameter being estimated is the

a. margin of error.

b. confidence coefficient.

c. same as α.

d. proportion estimate.

Hide Feedback

Correct

Solution

Correct Response

c

The general form of an interval estimate of a population mean or a population proportion is the _____ plus and minus the _____.

a. point estimate, margin of error

b. population proportion, standard error

c. population mean, standard error

d. planning value, confidence coefficient

Hide Feedback

Correct

Solution

Correct Response

a

The level of significance α

a. can be any positive value.

b. is (1 - confidence coefficient).

c. is always a negative value.

d. can be any value between -1.96 to 1.96.

Hide Feedback

Correct

Solution

Correct Response

b

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. With a .95 probability, the margin of error is approximately

a. 1.64.

b. .39.

c. .20.

d. 1.96.

Hide Feedback

Correct

Solution

Correct Response

b

In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determined. Assume a population standard deviation of 450 kilowatt-hours. If the sample mean is 1858 kWh, the 95% confidence interval estimate of the population mean is

a. 1758 to 1958 kWh.

b. 1760 to 1956 kWh.

c. 1776 to 1940 kWh.

d. 1729 to 1987 kWh.

Hide Feedback

Correct

Solution

Correct Response

b

From a population with a variance of 900, a sample of 225 items is selected. At 95% confidence, the margin of error is

a. 15.

b. 3.92.

c. 4.

d. 2.0.

Hide Feedback

Correct

Solution

Correct Response

b

The z value for a 97.8% confidence interval estimation is

a. 2.29.

b. 1.96.

c. 2.00.

d. 2.02.

Hide Feedback

Correct

Solution

Correct Response

a

A machine that produces a major part for an airplane engine is monitored closely. In the past, 10% of the parts produced would be defective. With a .95 probability, the sample size that needs to be taken if the desired margin of error is .04 or less is

a. 110.

b. 216.

c. 111.

d. 217.

Hide Feedback

Correct

Solution

Correct Response

d

The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3 minutes. It is known that the standard deviation of the population of checkout times is 1 minute. The standard error of the mean equals

a. .100.

b. 1.000.

c. .001.

d. .010.

Hide Feedback

Correct

Solution

Correct Response

a

A random sample of 64 SAT scores of students applying for merit scholarships showed an average of 1400 with a standard deviation of 240. If we want to provide a 95% confidence interval for the population mean SAT score, the degrees of freedom for reading the t value is

a. 63.

b. 60.

c. 61.

d. 62.

Hide Feedback

Correct

Solution

Correct Response

a

A probability sampling method in which we randomly select one of the first k elements and then select every k th element thereafter is

a. cluster sampling.

b. systematic sampling.

c. convenience sampling.

d. stratified random sampling.

Hide Feedback

Correct

Solution

Correct Response

b

The purpose of statistical inference is to provide information about the

a. population based upon information contained in the sample.

b. sample based upon information contained in the population.

c. mean of the sample based upon the mean of the population.

d. population based upon information contained in the population.

Hide Feedback

Correct

Solution

Correct Response

a

All of the following are true about the standard error of the mean except

a. its value is influenced by the standard deviation of the population.

b. it is larger than the standard deviation of the population.

c. it decreases as the sample size increases.

d. it measures the variability in sample means.

Hide Feedback

Correct

Solution

Correct Response

b

The sample mean is the point estimator of

a. p̄

b. x̄

c. σ

d. μ

Hide Feedback

Correct

Solution

Correct Response

d

Random samples of size 36 are taken from an infinite population whose mean and standard deviation are 20 and 15, respectively. The distribution of the population is unknown. The mean and the standard error of the mean are

a. 20 and 15

b. 36 and 15

c. 20 and 2.5

d. 20 and 0.417

Hide Feedback

Correct

Solution

Correct Response

c

A sample of 92 observations is taken from an infinite population. The sampling distribution of x̄ is approximately

a. normal because of the central limit theorem.

b. normal because the sample size is small in comparison to the population size.

c. normal because x̄ is always approximately normally distributed.

d. None of these alternatives are correct.

Hide Feedback

Correct

Solution

Correct Response

a

For a population with any distribution, the form of the sampling distribution of the sample mean is

a. always normal for large sample sizes.

b. always normal for all sample sizes.

c. sometimes normal for all sample sizes.

d. sometimes normal for large sample sizes.

Hide Feedback

Correct

Solution

Correct Response

a

A subset of a population selected to represent the population is

a. a small population.

b. a parameter.

c. a subset.

d. a sample.

Hide Feedback

Correct

Solution

Correct Response

d

A subset of a population selected to represent the population is

a. a small population.

b. a parameter.

c. a subset.

d. a sample.

Hide Feedback

Correct

Solution

Correct Response

d

A subset of a population selected to represent the population is

a. a small population.

b. a parameter.

c. a subset.

d. a sample.

Hide Feedback

Correct

Solution

Correct Response

d

The manager of a grocery store has taken a random sample of 100 customers. The average length of time it took these 100 customers to check out was 3 minutes. It is known that the standard deviation of the population of checkout times is 1 minute. With a .95 probability, the sample mean will provide a margin of error of

a. .10.

b. .196.

c. 1.64.

d. 1.96.

Hide Feedback

Correct

Solution

Correct Response

b

A random sample of 49 statistics examinations was taken. The average score, in the sample, was 84 with a variance of 12.25. The 95% confidence interval for the average examination score of the population of the examinations is

a. 77.40 to 86.60.

b. 80.48 to 87.52.

c. 82.99 to 85.01.

d. 68.00 to 100.00.

Hide Feedback

Correct

Solution

Correct Response

c

A sample of 200 elements from a population with a known standard deviation is selected. For an interval estimation of μ, the proper distribution to use is the

a. normal distribution.

b. t distribution with 201 degrees of freedom.

c. t distribution with 199 degrees of freedom.

d. t distribution with 200 degrees of freedom.

Hide Feedback

Correct

Solution

Correct Response

a

A sample of 200 elements from a population with a known standard deviation is selected. For an interval estimation of μ, the proper distribution to use is the

a. normal distribution.

b. t distribution with 201 degrees of freedom.

c. t distribution with 199 degrees of freedom.

d. t distribution with 200 degrees of freedom.

Hide Feedback

Correct

Solution

Correct Response

a

A random sample of 25 employees of a local company has been taken. A 95% confidence interval estimate for the mean systolic blood pressure for all employees of the company is 123 to 139. Which of the following statements is valid?

a. If the sampling procedure were repeated many times, 95% of the resulting confidence intervals would contain the population mean systolic blood pressure.

b. 95% of the sample of employees has a systolic blood pressure between 123 and 139.

c. 95% of the population of employees has a systolic blood pressure between 123 and 139.

d. If the sampling procedure were repeated many times, 95% of the sample means would be between 123 and 139.

Hide Feedback

Correct

Solution

Correct Response

a

From a population that is not normally distributed and whose standard deviation is not known, a sample of 6 items is selected to develop an interval estimate for the mean of the population (μ).

a. The sample size must be increased.

b. The normal distribution can be used.

c. The t distribution with 5 degrees of freedom must be used.

d. The t distribution with 6 degrees of freedom must be used.

Hide Feedback

Correct

Solution

Correct Response

a

The t value for a 95% confidence interval estimation with 24 degrees of freedom is

a. 1.711.

b. 2.064.

c. 2.069.

d. 2.492.

Hide Feedback

Correct

Solution

Correct Response

b

We are interested in conducting a study in order to determine the percentage of voters in a city who would vote for the incumbent mayor. What is the minimum sample size needed to estimate the population proportion with a margin of error not exceeding 4% at 95% confidence?

a. 601

b. 600

c. 626

d. 625

Hide Feedback

Correct

Solution

Correct Response

a

The use of the normal probability distribution as an approximation of the sampling distribution of p̄ is based on the condition that both np and n(1 - p) equal or exceed

a. .05.

b. 10.

c. 30.

d. 5.

Hide Feedback

Correct

Solution

Correct Response

d

It is known that the population variance equals 484. With a .95 probability, the sample size that needs to be taken if the desired margin of error is 5 or less is

a. 190.

b. 74.

c. 189.

d. 75.

Hide Feedback

Correct

Solution

Correct Response

d

A random sample of 121 bottles of cologne showed an average content of 4 ounces. It is known that the standard deviation of the contents (i.e., of the population) is 0.22 ounces. The point estimate of the mean content of the bottles is

a. 0.02

b. 121

c. 0.22

d. 4

Hide Feedback

Incorrect

Solution

Correct Response

d

The number of simple random samples of size 20 that can be selected from a finite population of size 25 is _____.

a. 20

b. 53,130

c. 1

d. 120

Hide Feedback

Correct

Solution

Correct Response

b

The population we want to make inferences about is the

a. frame.

b. target population.

c. finite population.

d. sampled population.

Hide Feedback

Correct

Solution

Correct Response

b

A random sample of 121 bottles of cologne showed an average content of 4 ounces. It is known that the standard deviation of the contents (i.e., of the population) is 0.22 ounces. The standard error of the mean equals

a. 0.0331

b. 0.3636

c. 0.0200

d. 4.000

Hide Feedback

Correct

Solution

Correct Response

c

The following data was collected from a simple random sample of a population.

13

15

14

16

12

If the population consisted of 10 elements, how many different random samples of size 6 could be drawn from the population?

a. 362880

b. 60

c. 3024

d. 210

Hide Feedback

Correct

Solution

Correct Response

d

Suppose candidate A for a town council seat receives 43% of the votes in an election. As voters leave the polls, they are asked who they voted for. What is the probability that less than 40% of the 80 voters surveyed indicate they voted for candidate A? Assume an infinite population.

a. .1368

b. .7061

c. .2939

d. .8632

Hide Feedback

Correct

Solution

Correct Response

c

The probability distribution of all possible values of the sample mean x̄ is

a. the probability density function of x̄.

b. the grand mean, since it considers all possible values of the sample mean.

c. one, since it considers all possible values of the sample mean.

d. the sampling distribution of x̄.

Hide Feedback

Correct

Solution

Correct Response

d

Parameters are

a. the averages taken from a sample.

b. numerical characteristics of either a sample or a population.

c. numerical characteristics of a population.

d. numerical characteristics of a sample.

Hide Feedback

Correct

Solution

Correct Response

c

A probability distribution of all possible values of a sample statistic is known as

a. a sampling distribution.

b. a parameter.

c. simple random sampling.

d. a sample statistic.

Hide Feedback

Correct

Solution

Correct Response

a

Suppose candidate A for a town council seat receives 43% of the votes in an election. As voters leave the polls, they are asked who they voted for. What is the probability that less than 40% of the 80 voters surveyed indicate they voted for candidate A? Assume an infinite population.

a. .8632

b. .2939

c. .1368

d. .7061

Hide Feedback

Incorrect

Check My Work Feedback

Incorrect: You did not respond to this question

Solution

Correct Response

b

How many different samples of size 3 can be taken from a finite population of size 10?

a. 30

b. 1,000

c. 720

d. 120

Hide Feedback

Correct

Solution

Correct Response

d

As a rule of thumb, the sampling distribution of the sample proportions can be approximated by a normal probability distribution whenever

a. n ≥ 30 and (1 - p) = 0.5.

b. np ≥5, n ≥30.

c. np ≥5 and n(1-p) ≥5.

d. None of these alternatives are correct.

Hide Feedback

Correct

Solution

Correct Response

c

In a local university, 40% of the students live in the dormitories. A random sample of 80 students is selected for a particular study. The probability that the sample proportion (the proportion living in the dormitories) is at least 0.30 is

a. 0.9328

b. 0.9664

c. 0.0336

d. 0.4664

Hide Feedback

Incorrect

Solution

Correct Response

b

In a local university, 40% of the students live in the dormitories. A random sample of 80 students is selected for a particular study. The probability that the sample proportion (the proportion living in the dormitories) is at least 0.30 is

a. 0.9328

b. 0.9664

c. 0.0336

d. 0.4664

Hide Feedback

Incorrect

Solution

Correct Response

b

The CEO of a large corporation is interested in the average salary of all managers for his large corporation. A sample of 500 managers found the average salary to be $56,500. Which of the following statements is correct?

a. The value $56,500 is a parameter.

b. The population size is 500 managers.

c. The average salary for all the managers will also be $56,500.

d. The average salary for the 500 managers can be used to estimate the average salary for all the managers.

Hide Feedback

Correct

Solution

Correct Response

d

The proportion of students at a university who pass a biology class is p = .86. If 50 students are randomly selected, what is the probability that at least 75% of them have passed the class?

a. .9638

b. .9875

c. .0362

d. .0125

Hide Feedback

Correct

Solution

Correct Response

b

Given the sampling distribution of the sample mean shown here, which of the following values is a reasonable estimate for the population mean?

a. 280

b. 300

c. .27

d. 320

Hide Feedback

Correct

Solution

Correct Response

b

In point estimation

a. data from the sample is used to estimate the sample statistic.

b. the mean of the population equals the mean of the sample.

c. data from the sample is used to estimate the population parameter.

d. data from the population is used to estimate the population parameter.

Hide Feedback

Correct

Solution

Correct Response

c

In point estimation

a. data from the sample is used to estimate the sample statistic.

b. the mean of the population equals the mean of the sample.

c. data from the sample is used to estimate the population parameter.

d. data from the population is used to estimate the population parameter.

Hide Feedback

Correct

Solution

Correct Response

c

The sample mean is the point estimator of

a. μ

b. p̄

c. x̄

d. σ

Hide Feedback

Correct

Solution

Correct Response

a

A population has a mean of 84 and a standard deviation of 12. A sample of 36 observations will be taken. The probability that the sample mean will be between 80.54 and 88.9 is

a. 0.7200

b. 8.3600

c. 0.0347

d. 0.9511

Hide Feedback

Correct

Solution

Correct Response

d

When the selection of one element from the population influences the selection of another element, the sample

a. is from a finite population.

b. was selected using computer-generated random numbers.

c. contains selection bias.

d. is a simple random sample.

Hide Feedback

Correct

Solution

Correct Response

c

The desired situation is when

a. the sampled population is larger than the targeted population.

b. the sampled population is smaller than the targeted population.

c. the sampled population is identical to the targeted population.

d. the sampled population is more varied than the targeted population.

Hide Feedback

Correct

Solution

Correct Response

c

A sample of 25 observations is taken from an infinite population. The sampling distribution of p̄ is

a. not normal since n < 30

b. approximately normal because p̄ is always normally distributed

c. approximately normal if np > 30 and n(1-P) > 30

d. approximately normal if np ≥ 5 and n(1-P) ≥ 5

Hide Feedback

Incorrect

Solution

Correct Response

d

Sampling distribution of x̄ is the

a. probability distribution of the sample proportion.

b. mean of the sample.

c. mean of the population.

d. probability distribution of the sample mean.

Hide Feedback

Correct

Solution

Correct Response

d

Which of the following sampling methods does not lead to probability samples?

a. Stratified sampling

b. Cluster sampling

c. Systematic sampling

d. Convenience sampling

Hide Feedback

Correct

Solution

Correct Response

d

A single numerical value used as an estimate of a population parameter is known as

a. a parameter.

b. a population parameter.

c. a mean estimator.

d. a point estimate.

Hide Feedback

Correct

Solution

Correct Response

d

A single numerical value used as an estimate of a population parameter is known as

a. a parameter.

b. a population parameter.

c. a mean estimator.

d. a point estimate.

Hide Feedback

Correct

Solution

Correct Response

d

A single numerical value used as an estimate of a population parameter is known as

a. a parameter.

b. a population parameter.

c. a mean estimator.

d. a point estimate.

Hide Feedback

Correct

Solution

Correct Response

d

A sample of 75 information systems managers had an average hourly income of $40.75 with a standard deviation of $7.00. The standard error of the mean is

a. 1.611.

b. .8083.

c. 7.0.

d. 80.83.

Hide Feedback

Incorrect

Solution

Correct Response

b

Which of the following is not required when computing the sample size for an interval estimate of the population mean?

a. Population mean

b. Population standard deviation

c.

d. Margin of error the researcher is willing to accept

Hide Feedback

Correct

Solution

Correct Response

a

We are interested in conducting a study in order to determine the percentage of voters in a city who would vote for the incumbent mayor. What is the minimum sample size needed to estimate the population proportion with a margin of error not exceeding 4% at 95% confidence?

a. 601

b. 600

c. 626

d. 625

Hide Feedback

Correct

Solution

Correct Response

a

From a population that is normally distributed, a sample of 25 elements is selected and the standard deviation of the sample is computed. For the interval estimation of μ, the proper distribution to use is the

a. t distribution with 25 degrees of freedom.

b. normal distribution.

c. t distribution with 24 degrees of freedom.

d. t distribution with 26 degrees of freedom.

Hide Feedback

Correct

Solution

Correct Response

c

A population has a standard deviation of 50. A random sample of 100 items from this population is selected. The sample mean is determined to be 600. At 95% confidence, the margin of error is

a. 8.225.

b. 8.3.

c. 9.92.

d. 9.8.

Hide Feedback

Correct

Solution

Correct Response

d

Using an α = .04, a confidence interval for a population proportion is determined to be .65 to .75. For the same data, if α is decreased, the confidence interval for the population proportion

a. uses a zero margin of error.

b. becomes narrower.

c. remains the same.

d. becomes wider.

Hide Feedback

Correct

Solution

Correct Response

d

In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determined. Assume a population standard deviation of 450 kilowatt-hours. The standard error of the mean is

a. 450.

b. 500.

c. 81.

d. 50.

Hide Feedback

Correct

Solution

Correct Response

d

In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determined. Assume a population standard deviation of 450 kilowatt-hours. The standard error of the mean is

a. 450.

b. 500.

c. 81.

d. 50.

Hide Feedback

Correct

Solution

Correct Response

d

In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determined. Assume a population standard deviation of 450 kilowatt-hours. The standard error of the mean is

a. 450.

b. 500.

c. 81.

d. 50.

Hide Feedback

Correct

Solution

Correct Response

d

In order to estimate the average electric usage per month, a sample of 81 houses was selected and the electric usage was determined. Assume a population standard deviation of 450 kilowatt-hours. The standard error of the mean is

a. 450.

b. 500.

c. 81.

d. 50.

Hide Feedback

Correct

Solution

Correct Response

d

The t distribution is a family of similar probability distributions, with each individual distribution depending on a parameter known as the

a. standard deviation.

b. sample size.

c. degrees of freedom.

d. finite correction factor.

Hide Feedback

Correct

Solution

Correct Response

c

The degrees of freedom associated with a t distribution are a function of the

a. area in the upper tail.

b. sample standard deviation.

c. confidence coefficient.

d. sample size.

Hide Feedback

Correct

Solution

Correct Response

d

From a population that is not normally distributed and whose standard deviation is not known, a sample of 6 items is selected to develop an interval estimate for the mean of the population (μ).

a. The t distribution with 5 degrees of freedom must be used.

b. The normal distribution can be used.

c. The t distribution with 6 degrees of freedom must be used.

d. The sample size must be increased.

Hide Feedback

Correct

Solution

Correct Response

d

The manager of a department store wants to determine the proportion of customers who use the store's credit card when making a purchase. What sample size should he select so that at 96% confidence the error will not be more than 10%?

a. 106

b. 76

c. 1

d. There is not enough information given to determine the sample size.

Hide Feedback

Correct

Solution

Correct Response

a

Using an α = .04, a confidence interval for a population proportion is determined to be .65 to .75. For the same data, if α is decreased, the confidence interval for the population proportion

a. uses a zero margin of error.

b. becomes narrower.

c. becomes wider.

d. remains the same.

Hide Feedback

Correct

Solution

Correct Response

c

A population has a standard deviation of 50. A random sample of 100 items from this population is selected. The sample mean is determined to be 600. At 95% confidence, the margin of error is

a. 8.3.

b. 9.92.

c. 9.8.

d. 8.225.

Hide Feedback

Correct

Solution

Correct Response

c

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. With a .95 probability, the margin of error is approximately

a. 1.64.

b. 1.96.

c. .20.

d. .39.

Hide Feedback

Correct

Solution

Correct Response

d

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. With a .95 probability, the margin of error is approximately

a. 1.64.

b. 1.96.

c. .20.

d. .39.

Hide Feedback

Correct

Solution

Correct Response

d

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. With a .95 probability, the margin of error is approximately

a. 1.64.

b. 1.96.

c. .20.

d. .39.

Hide Feedback

Correct

Solution

Correct Response

d

In order to estimate the average time spent per student on the computer terminals at a local university, data were collected for a sample of 81 business students over a one-week period. Assume the population standard deviation is 1.8 hours. With a .95 probability, the margin of error is approximately

a. 1.64.

b. 1.96.

c. .20.

d. .39.

Hide Feedback

Correct

Solution

Correct Response

d

As the sample size increases, the margin of error

a. decreases.

b. stays the same.

c. increases.

d. fluctuates depending on the mean.

Hide Feedback

Correct

Solution

Correct Response

a

When s is used to estimate σ, the margin of error is computed by using the

a. t distribution.

b. mean of the sample.

c. normal distribution.

d. mean of the population.

Hide Feedback

Correct

Solution

Correct Response

a

What value of p should be used to compute the sample size that guarantees all estimates of proportions will meet the margin of error requirement?

a. 0.01

b. 0.25

c. 1

d. 0.50

Hide Feedback

Correct

Solution

Correct Response

d

We can use the normal distribution to make confidence interval estimates for the population proportion, p, when

a. p has a normal distribution.

b. np ≥ 5.

c. both np ≥ 5 and n(1 - p) ≥ 5.

d. n(1 - p) ≥ 5.

Hide Feedback

Correct

Solution

Correct Response

c

Which of the following must be decided by the researcher when computing the minimum sample size for an interval estimate of μ or p?

a. Mean

b. Standard deviation

c. Degrees of freedom

d. Margin of error

Hide Feedback

Correct

Solution

Correct Response

d

The value added to and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the

a. parameter estimate.

b. confidence level.

c. margin of error.

d. planning value.

Hide Feedback

Correct

Solution

Correct Response

c

The value added to and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the

a. parameter estimate.

b. confidence level.

c. margin of error.

d. planning value.

Hide Feedback

Correct

Solution

Correct Response

c

The value added to and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the

a. parameter estimate.

b. confidence level.

c. margin of error.

d. planning value.

Hide Feedback

Correct

Solution

Correct Response

c

The value added to and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the

a. parameter estimate.

b. confidence level.

c. margin of error.

d. planning value.

Hide Feedback

Correct

Solution

Correct Response

c

The value added to and subtracted from a point estimate in order to develop an interval estimate of the population parameter is known as the

a. parameter estimate.

b. confidence level.

c. margin of error.

d. planning value.

Hide Feedback

Correct

Solution

Correct Response

c