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BA6933 Week-4 Asst-(10,11,12)

 

Consider the following hypothesis test.

 

 

Excel File: data10-03.xlsx

  Sample 1

  Sample 2

 

 

Enter negative values as negative numbers.

a. What is the value of the test statistic? (to 2 decimals)
 

b. What is the -value? (to 4 decimals)
 

c. With , what is your hypothesis testing conclusion?
 



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Consumer Reports uses a survey of readers to obtain customer satisfaction ratings for the nation's largest supermarkets (Consumer Reports website). Each survey respondent is asked to rate a specified supermarket based on a variety of factors such as quality of products, selection, value, checkout efficiency, service, and store layout. An overall satisfaction score summarizes the rating for each respondent with  meaning the respondent is completely satisfied in terms of all factors. Sample data representative of independent samples of Publix and Trader Joe's customers are shown below.

Excel File: data10-07.xlsx

  Publix

Trader Joe's

a. Formulate the null and alternative hypotheses to test whether there is a difference between the population mean customer satisfaction scores for the two retailers.

  

  

b. Assume that experience with the Consumer Reports satisfaction rating scale indicates that a population standard deviation of  is a reasonable assumption for both retailers. Conduct the hypothesis test and report the -value.

-value =   (to  decimals)

At a  level of significance what is your conclusion?

       I.      Reject . There is not sufficient evidence to conclude that the mean satisfaction scores differ for the two retailers.

     II.      Do not reject . There is not sufficient evidence to conclude that the mean satisfaction scores differ for the two retailers.

    III.      Reject . There is sufficient evidence to conclude that the mean satisfaction scores differ for the two retailers.

    IV.      Do not reject . There is sufficient evidence to conclude that the mean satisfaction scores differ for the two retailers.

 

c. Which retailer, if either, appears to have the greater customer satisfaction?

 

Provide a  confidence interval for the difference between the population mean customer satisfaction scores for the two retailers. Enter negative values as negative numbers, if any.

  to   (to  decimals)



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Consider the following data for two independent random samples taken from two normal populations.

Excel File: 
data10-11.xlsx

Sample 1

10

7

13

7

9

8

Sample 2

8

7

8

4

6

9

a. Compute the two sample means. (to nearest whole number)
 
 
 
 

b. Compute the two sample standard deviations. (to 2 decimals)
 
 
 
 

c. What is the point estimate of the difference between the two population means?
 

d. What is the  confidence interval estimate of the difference between the two population means? (to 2 decimals and enter negative value as negative number)
(
 ,  )



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The increasing annual cost (including tuition, room, board, books and fees) to attend college ) to attend college has been widely discussed in many publications including Money magazine. The following random samples show the annual cost of attending private and public colleges. Data are in thousands of dollars. Click on the datafile logo to reference the data. Round degrees of freedom to the preceding whole number.

Private Colleges

52.8

43.2

45.0

33.3

44.0

 

30.6

45.8

37.8

50.5

42.0

 

Public Colleges

20.3

22.0

28.2

15.6

24.1

28.5

22.8

25.8

18.5

25.6

14.4

21.8

a. Compute the sample mean and sample standard deviation for private and public colleges. Round your answers to two decimal places.

 =  

 =  

 =  

 =  

b. What is the point estimate of the difference between the two population means? Round your answer to one decimal place.
 

Interpret this value in terms of the annual cost of attending private and public colleges.
 
 

c. Develop a  confidence interval of the difference between the mean annual cost of attending private and public colleges.

 confidence interval, private colleges have a population mean annual cost    to    more expensive than public colleges.



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Periodically, Merrill Lynch customers are asked to evaluate Merrill Lynch financial consultants and services. Higher ratings on the client satisfaction survey indicate better service with  the maximum service rating. Independent samples of service ratings for two financial consultants are summarized here. Consultant A has  years of experience, whereas consultant B has  year of experience. Use  and test to see whether the consultant with more experience has the higher population mean service rating. Round degrees of freedom to previous whole number.

Excel File: data10-17.xlsx

Consultant A

Consultant B

a. State the null and alternative hypotheses.
:  
 
:  
 

b. Compute the value of the test statistic. (to 2 decimals)
 

c. What is the p-value? Use Table 2 from Appendix B to find the values that bound the test statistic.
    

d. What is your conclusion?
 



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Bank of America's Consumer Spending Survey collected data on annual credit card charges in seven different categories of expenditures: transportation, groceries, dining out, household expenses, home furnishings, apparel, and entertainment. Using data from a sample of  credit card accounts, assume that each account was used to identify the annual credit card charges for groceries (population 1) and the annual credit card charges for dining out (population 2). Using the difference data, the sample mean difference was  , and the sample standard deviation was .

a. Formulate the null and alternative hypotheses to test for no difference between the population mean credit card charges for groceries and the population mean credit card charges for dining out.
 
 
 
 

b. Use  level of significance. Can you conclude that the population means differ?
 

What is the -value? (to 6 decimals)
 

c. Which category, groceries or dining out, has a higher population mean annual credit card charge?
 

What is the point estimate of the difference between the population means? Round to the nearest whole number.
 

What is the  confidence interval estimate of the difference between the population means? Round to the nearest whole number.
 
 ,   



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The College Board SAT college entrance exam consists of two sections: math and evidence-based reading and writing (EBRW). Sample data showing the math and EBRW scores for a sample of  students who took the SAT follow. Click on the datafile logo to reference the data.

Student

Math

EBRW

Student

Math

EBRW

1

540

474

7

480

430

2

432

380

8

499

459

3

528

463

9

610

615

4

574

612

10

572

541

5

448

420

11

390

335

6

502

526

12

593

613

a. Use a  level of significance and test for a difference between the population mean for the math scores and the population mean for the EBRW scores.

What is the test statistic? Enter negative values as negative numbers. Round your answer to two decimal places.
 
 

What is the -value? Round your answer to four decimal places.
 

What is your conclusion?

       I.      Reject . We cannot conclude that there is a significant difference between the population mean scores for the SAT math test and the SAT writing test.

     II.      Do not reject . We cannot conclude that there is a significant difference between the population mean scores for the SAT math test and the SAT writing test.

    III.      Reject . We can conclude that there is a significant difference between the population mean scores for the SAT math test and the SAT writing test.

    IV.      Do not reject . We can conclude that there is a significant difference between the population mean scores for the SAT math test and the SAT writing test.

 

b. What is the point estimate of the difference between the mean scores for the two tests?
 

What are the estimates of the population mean scores for the two tests?

Math test

 

EBRW test

 

Which test reports the higher mean score?
 



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A personal fitness produces both a deluxe and a standard model of a smoothie blender for home use. Selling prices obtained from a sample of retail outlets follow.

Excel File: data10-27.xlsx

Model Price ($)

Model Price ($)

Retail Outlet

Deluxe

Standard

Retail Outlet

Deluxe

Standard

1

39

27

5

40

30

2

39

28

6

39

34

3

45

35

7

35

29

4

38

30

Round your answers to 2 decimal places.

a. The manufacturer's suggested retail prices for the two models show a  price differential. Use a  level of significance and test that the mean difference between the prices of the two models is  .

 

b. What is the  confidence interval for the difference between the mean prices of the two models?

  to  



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Consider the hypothesis test below.

The following results are for independent samples taken from the two populations.

Sample 1

Sample 2

 

 


Use pooled estimator of .

a. What is the -value (to 4 decimals)? Use Table 1 from Appendix B.
 

b. With , what is your hypothesis testing conclusion?
 



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Tourism is extremely important to the economy of Florida. Hotel occupancy is an often-reported measure of visitor volume and visitor activity (Orlando Sentinel, May , ). Hotel occupancy data for February in two consecutive years are as follows.

Current Year

Previous Year

Occupied Rooms

1,470

1,360

Total Rooms

1,750

1,700

a. Formulate the hypothesis test that can be used to determine whether there has been an increase in the proportion of rooms occupied over the one-year period.

Let

 population proportion of rooms occupied for current year

 population proportion of rooms occupied for previous year

  
 
 

b. What is the estimated proportion of hotel rooms occupied each year (to  decimals)?

Current year

 

Previous Year

 

c. Conduct a hypothesis test. What is the -value (to  decimals)? Use Table 1 from Appendix B.

-value =  

Using a  level of significance, what is your conclusion?

We   that there has been an increase in the hotel occupancy rate.

d. What is the  confidence interval estimate of the change in occupancy for the one-year period (to  decimals)?

  to  

Do you think area officials would be pleased with the results?

Officials would likely be   with the occupancy statistics as the trend for the current year is   in hotel occupancy rates compared to last year.



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The National Association of Home Builders provided data on the cost of the most popular home remodeling projects. Sample data on cost in thousands of dollars for two types of remodeling projects are as follows.

Excel File: data10-41.xlsx

Kitchen

Master Bedroom

Kitchen

Master Bedroom

25.2

18.0

23.0

17.8

17.4

22.9

19.7

24.6

22.8

26.4

16.9

21.0

21.9

24.8

21.8

19.7

26.9

23.6

a. Develop a point estimate of the difference between the population mean remodeling costs of kitchens and master bedrooms. (Enter negative values as negative numbers. Report in thousands of dollars with no commas in your answer.)
Point estimate  
  thousand

b. Develop a  confidence interval for the difference between the two population means. (to 1 decimal and enter negative values as negative numbers)
(
 ,  ) in thousands of dollars.



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Country Financial, a financial services company, uses surveys of adults age  and older to determine whether personal financial fitness is changing over time. A recent sample of  adults showed  indicating that their financial security was more than fair. Just a year prior, a sample of  adults showed  indicating that their financial security was more than fair.

a. State the hypotheses that can be used to test for a significant difference between the population proportions for the two years.
 
 
 
 

b. Conduct the hypothesis test and compute the -value. Round your answer to four decimal places.
-value = 
 

At  level of significance, what is your conclusion?

       I.      Reject . There is not sufficient evidence to conclude that the population proportions are not equal. The data do not suggest that there has been a change in the population proportion saying that their financial security is more than fair.

     II.      Reject . There is sufficient evidence to conclude that the population proportions are not equal. The data suggest that there has been a change in the population proportion saying that their financial security is more than fair.

    III.      Do not reject . There is not sufficient evidence to conclude that the population proportions are not equal. The data do not suggest that there has been a change in the population proportion saying that their financial security is more than fair.

    IV.      Do not reject . There is sufficient evidence to conclude that the population proportions are not equal. The data suggest that there has been a change in the population proportion saying that their financial security is more than fair.

 

c. What is the  confidence interval estimate of the difference between the two population proportions? Round your answers to four decimal places.
 Confidence Interval (
  to  )



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Each year, over  million people in the United States become infected with bacteria that are resistant to antibiotics. In particular, the Centers of Disease Control and Prevention has launched studies of drug-resistant gonorrhea (CDC.gov website). Of  cases tested in Alabama,  were found to be drug-resistant. Of  cases tested in Texas,  were found to be drug-resistant. Do these data suggest a statistically significant difference between the proportions of drug-resistant cases in the two states? Use a  level of significance. What is the -value, and what is your conclusion?

Test statistic =   (to 2 decimals)

-value =   (to 4 decimals)

Conclusion:  

Choose the correct option.

There is a significant difference in drug resistance between the two states. Alabama has the higher drug resistance rate.

 



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Find the following chi-square distribution values from Table 11.1 or Table 3 of Appendix B. (to  decimals)

a.  with 
 

b.  with 
 

c.  with 
 

d.  with 
 

e.  with 
 



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In , Mike Krzyewski and John Calipari topped the list of highest paid college basketball coaches (Sports Illustrated website). The following sample shows the head basketball coach's salary for a sample of  schools playing NCAA Division I basketball. Salary data are in millions of dollars.

Excel File: data11-05.xlsx

University

Coach's Salary

University

Coach's Salary

North Carolina State

2.2

Miami (FL)

1.5

Iona

0.5

Creighton

1.3

Texas A&M

2.4

Texas Tech

1.5

Oregon

2.7

South Dakota State

0.3

Iowa State

2.0

New Mexico State

0.3

a. Use the sample mean for the  schools to estimate the population mean annual salary for head basketball coaches at colleges and universities playing NCAA Division I basketball (to  decimals).

$    million

b. Use the data to estimate the population standard deviation for the annual salary for head basketball coaches (to  decimals).

$    million

c. What is the  confidence interval for the population variance (to  decimals)? Use Table 11.1.

($    million, $    million)

d. What is the  confidence interval for the population standard deviation (to  decimals)? Use Table 11.1.

($    million, $    million)



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In , Americans spent a record-high  billion on Halloween-related purchases (the balance website). Sample data showing the amount, in dollars,  adults spent on a Halloween costume are as follows.

10

70

21

61

30

37

32

43

54

16

15

99

45

31

65

28

a. What is the estimate of the population mean amount adults spend on a Halloween costume (to  decimals)?

  

b. What is the sample standard deviation (to  decimals)?

  

c. Provide a  confidence interval estimate of the population standard deviation for the amount adults spend on a Halloween costume (to  decimals). Use Table 11.1.

      



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The competitive advantage of some small American factories such as In Tolerance Contract Manufacturing lies in their ability to produce parts with very narrow requirements, or tolerances, that are typical in the aerospace industry. Consider a product with specifications that call for a maximum variance in the lengths of the parts of . Suppose the sample variance for  parts turns out to be . Use , to test whether the population variance specification is being violated.

 
 

Test statistic =   (to 2 decimals, if required)

The -value is  . Use Table 11.1.

 

 



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Find the following  distribution values from Table 4 of Appendix B (available online).

a.  with degrees of freedom  and 

 

b.  with degrees of freedom  and 

 

c.  with degrees of freedom  and 

 

d.  with degrees of freedom  and 

 



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In its  Auto Reliability Survey, Consumer Reports asked subscribers to report their maintenance and repair costs. Most individuals are aware of the fact that the average annual repair cost for an automobile depends on the age of the automobile. A researcher is interested in finding out whether the variance of the annual repair costs also increases with the age of the automobile. A sample of  automobiles  years old showed a sample standard deviation for annual repair costs of  and a sample of  automobiles  years old showed a sample standard deviation for annual repair costs of .

a. State the null and alternative versions of the research hypothesis that the variance in annual repair costs is larger for the older automobiles. Let  year old automobiles be represented by population .

   

   

b. At a  level of significance, what is your conclusion?

Calculate the value of the test statistic (to  decimals).

 

The -value is  . Use Table 4 of Appendix B.

  that  year old automobiles have a larger variance in annual repair costs compared to  year old automobiles.



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The variance in a production process is an important measure of the quality of the process. A large variance often signals an opportunity for improvement in the process by finding ways to reduce the process variance. Jelly Belly Candy Company is testing two machines that use different technologies to fill three pound bags of jelly beans. The file Bags contains a sample of data on the weights of bags (in pounds) filled by each machine.Conduct a statistical test to determine whether there is a significant difference between the variances in the bag weights for the two machines. Use a  level of significance. What is your conclusion? Which machine, if either, provides the greater opportunity for quality improvements? Click on the datafile logo to reference the data.

   (to  decimals)

   (to  decimals)

   (to  decimals)

 

 



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Battery life is an important issue for many smartphone owners. Public health studies have examined "low-battery anxiety" and acute anxiety called "nomophobia" that results when a smartphone user's phone battery charge runs low and then dies (Wall Street Journal, May , ). Battery life between charges for the Samsung Galaxy S9 averages  hours when the primary use is talk time and  hours when the primary use is Internet applications. Because the mean hours for talk time usage is greater than the mean hours for Internet usage, the question was raised as to whether the variance in hours of usage is also greater when the primary use is talk time. Sample data showing battery life between charges for the two applications follows. Click on the datafile logo to reference the data.

Primary Use: Talking

35.8

22.2

24.0

32.6

18.5

42.5

28.0

23.8

30.0

22.8

20.3

35.5

Primary Use: Internet

14.0

12.5

16.4

11.9

9.9

3.1

5.4

11.0

15.2

4.0

4.7

a. Formulate hypotheses about the two population variances that can be used to determine whether the population variance in battery life is greater for the talk time application. Consider the talk time use as population  and Internet use as population .

   
 
  

b. What are the standard deviations of battery life for the two samples (to  decimals)?

  

  

c. Conduct the hypothesis test and compute the -value.

-value =   (to  decimals)

Using a  level of significance, what is your conclusion?

  . We   that the population variance in battery hours of use for the talk time application is larger than the population variance in battery hours of use for the Internet application.



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Because of staffing decisions, managers of the Gibson-Marimont Hotel are interested in the variability in the number of rooms occupied per day during a particular season of the year. A sample of  days of operation shows a sample mean of  rooms occupied per day and a sample standard deviation of  rooms.

a. What is the point estimate of the population variance (to nearest whole number)?

 

b. Provide a  confidence interval estimate of the population variance (to nearest whole number). Use Table 11.1.

( ,  )

c. Provide a  confidence interval estimate of the population standard deviation (to  decimal). Use Table 11.1.

( ,  )



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According to the  Corporate Travel Index compiled by Business Travel News, the average daily cost for business travel in the United States rose to  per day (Executive Travel website). The file Travel contains sample data for an analogous study on the estimated daily living costs for an executive traveling to various international cities. The estimates include a single room at a four-star hotel, beverages, breakfast, taxi fares, and incidental costs. Click on the datafile logo to reference the data.

City

Daily Living Cost ($)

City

Daily Living Cost ($)

Bangkok

242.87

Mexico City

212.00

Bogota

260.93

Milan

284.08

Cairo

194.19

Mumbai

139.16

Dublin

260.76

Paris

436.72

Frankfurt

355.36

Rio de Janeiro

240.87

Hong Kong

346.32

Seoul

310.41

Johannesburg

165.37

Tel Aviv

223.73

Lima

250.08

Toronto

181.25

London

326.76

Warsaw

238.20

Madrid

283.56

Washington, D.C.

250.61

a. Compute the sample mean (to  decimals).
 
 

b. Compute the sample standard deviation (to  decimals).
 
 

c. Compute a  confidence interval for the population standard deviation (to  decimals). Use Table 11.1.
 (
 ,  )



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Filling boxes with consistent amounts of its cereals are critical to General Mills’ success. The filling variance for boxes of Count Chocula cereal is designed to be  ounces2 or less. A sample of  boxes of Count Chocula shows a sample standard deviation of  ounces. Use  to determine whether the variance in the cereal box fillings is exceeding the design specification. Use Table 11.1.

   
 
  

Test statistic =   (to  decimals)

 

Interpret: The population variance appears to be exceeding the standard.

 



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A sample of  days over the past six months showed that that Philip Sherman, DDS, treated the following numbers of patients: , , , , , , , , and . If the number of patients seen per day is normally distributed, would an analysis of these sample data reject the hypothesis that the variance in the number of patients seen per day is equal to ? Use  level of significance. Use Table 3 from Appendix B.

State the hypotheses.

:    10

:    10

Calculate the variance and test statistic. (to 2 decimals)

variance =  

test statistic =  

What is your conclusion?

 



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Stable cost reporting in a manufacturing setting is typically a sign that operations are running smoothly. The accounting department at Rockwell Collins, an avionics manufacturer, analyzes the variance of the weekly costs reported by two of its production departments. A sample of  cost reports for each of the two departments shows cost variances of  and , respectively. Is this sample sufficient to conclude that the two production departments differ in terms of unit cost variance? Use  (to  decimals).

   
 
  

Test statistic =  

 



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During the first  weeks of the television season, the Saturday evening 8:00 P.M. to 9:00 P.M. audience proportions were recorded as ABC , CBS , NBC , and Independents . A sample of  homes two weeks after a Saturday night schedule revision yielded the following viewing audience data: ABC  homes, CBS  homes, NBC  homes, and Independents  homes. Test with  to determine whether the viewing audience proportions changed.

Find the test statistic and p-value. (Round your test statistic to two decimal places. Use Table 3 of Appendix B.)

Test statistic =  

-value is  .

Conclusion:
There is 
  change in the viewing audience proportions.



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The following table contains observed frequencies for a sample of .

Column Variable

Row Variable

A

B

C

P

35

50

40

Q

15

20

40

Test for independence of the row and column variables using  .

Compute the value of the  test statistic (to 2 decimals).

 

Use Table 3 of Appendix B to find the -value.

The -value is  

What is your conclusion?

 



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In , Addison Group and Kelton surveyed the work preferences and attitudes of  working adults spread over three generations — Baby Boomers, Generation X, and Millennials (Society for Human Resource Management website). One question asked individuals if they would leave their current job to make more money at another job. The file Millennials contains the sample data, which is also summarized in the following table.

Click on the datafile logo to reference the data.

Generation

Leave Job for

More Money?

Baby Boomer

Generation X

Millennial

Yes

122

141

155

No

191

176

163

Conduct a test of independence to determine whether interest in leaving a current job for more money is independent of employee generation.

Compute the value of the  test statistic (to  decimals). Do not round your intermediate calculation.

 

What is the -value? Use Table 3 of Appendix B.

The -value is  .

Using a  level of significance, what is your conclusion?

Conclude interest in leaving job for more money   independent of the employee generation.



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The Wall Street Journal Corporate Perceptions Study surveys readers and asks how each rats the quality of management and the reputation of the company for over  worldwide corporations. Both the quality of management and the reputation of the company were rated on an excellent, good, and fair categorical scale. Assume the sample data for  respondents below applies to this study.

Excel File: 
data12-13.xlsx

Reputation of Company

Quality of Management

Excellent

Good

Fair

Excellent

40

25

5

Good

35

35

10

Fair

25

10

15

a. Use  level of significance and test for independence of the quality of management and the reputation of the company.

Compute the value of the  test statistic (to 2 decimals). Do not round intermediate calculations.
 

Use Table 3 of Appendix B to find the -value.

The -value is  

What is your conclusion?
Conclude that the rating for the quality of management is 
  of the rating for the reputation of the company.

b. If there is a dependence or association between the two ratings, discuss and use probabilities to justify your answer.
The highest probabilities are that the two variables will 
 .



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Use the sample data below to test the hypotheses

: Not all population proportions are the same

where  is the population proportion of Yes responses for population .

Populations

Response

1

2

3

Yes

150

150

94

No

100

150

106

Using a  level of significance, what is the -value? Use Table 3 of Appendix B.

The -value is  

What is your conclusion?
  all population proportions are equal.



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The following sample data represent the number of late and on time flights for the Delta, United and US Airways.

Excel File: data12-19.xlsx

Airline

Flight

Delta

United

US Airways

Late

39

51

56

On Time

261

249

344

a. Formulate the hypotheses for a test that will determine whether the population proportion of late flights is the same for all three airlines.

  

  

b. Conduct the hypothesis test with a  level of significance. What is the -value? Use Table 3 of Appendix B.

The p-value is  

What is your conclusion?

 

c. Compute the sample proportion of late flights for each airline.

   (to 2 decimals)

   (to 2 decimals)

   (to 2 decimals)

What is the overall proportion of late flights for the three airlines? Round your answer to three decimal places.

The overall proportion of late flights for the three airlines is  



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Kate Sanders, a researcher in the department of biology at IPFW University, studied the effect of agriculture contaminants on the stream fish population in northeastern Indiana. Specially designed traps collected samples of fish at each of four stream locations. A research question was, Did the differences in agricultural contaminants found at the four locations alter the proportion of the fish population by gender? Observed frequencies were as follows.

Excel File: data12-21.xlsx

Stream Locations

Gender

A

B

C

D

Male

49

44

49

39

Female

41

46

36

44

a. Focusing on the proportion of male fish at each location, test the hypothesis that the population proportions are equal for all four locations. Use a  level of significance.

1. 

2. 

3. 

Choose correct answer from above choice

 

 

What is the -value? Use Table 3 of Appendix B.

The -value is  

What is your conclusion?

 

b. Does it appear that differences in agricultural contaminants found at the four locations altered the fish population by gender?

 



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Social media is popular around the world. Statista provides estimate of the number of social media users in various countries in  as well as the projections for . Assume that the results for surveys in the United Kingdom, China, Russia, and the United States are as follows.

Excel File: data12-23.xlsx

Country

Use Social

United

United

Media

Kingdom

China

Russia

States

Yes

480

215

343

640

No

320

285

357

360

a. Conduct a hypothesis test to determine whether the proportion of adults using social media is equal for all four countries. Using a  level of significance.

1. 

2. 

3. 

Choose correct answer from above choice
 

H a 

What is the -value? Use Table 3 of Appendix B.

The -value is  

What is your conclusion?

Conclude the all population proportions are  .

b. What are the sample proportions for each of the four countries? Round your answers to two decimal places.

United Kingdom

 

China

 

Russia

 

United States

 

Which country has the largest proportion of adults using social networking sites?
 

c. Using a  level of significance, conduct multiple pairwise comparison tests among the four countries. Round  ,  and  to two decimal places. Round  to four decimal places.

Comparison

UK vs C

 

 

 

 

 

 

 

UK vs R

 

 

 

 

 

 

 

UK vs US

 

 

 

 

 

 

 

C vs R

 

 

 

 

 

 

 

C vs US

 

 

 

 

 

 

 

R vs US

 

 

 

 

 

 

 

What is your conclusion?

Only two comparisons are not significant  . All other comparisons show a significant difference.



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Historically, the industries with the most complaints to the Better Business Bureau have been banks, cable and satellite television companies, collection agencies, cellular phone providers, and new car dealerships. The results for a sample of  complaints are contained in the file BBB. Click on the datafile logo to reference the data.

a. Construct a frequency distribution for the number of complaints by industry.


Category

Observed
Frequency

Bank

 

Cable

 

Car

 

Cell

 

Collection

 

Total

 

b. Using , conduct a hypothesis test to determine whether the probability of a complaint is the same for the five industries.

The test-statistic is   (to 3 decimals).

-value    (to 4 decimals)

What is your conclusion?

 

c. Which industry has the most complaints?

 

Dropping the industry with the most complaints using , conduct a hypothesis test to determine whether the probability of a complaint is the same for the remaining four industries.

The test-statistic is   (to 3 decimals).

-value    (to 4 decimals)

What is your conclusion?

 



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Based on  sales, the six top-selling compact cars are the Honda Civic, Toyota Corolla, Nissan Sentra, Hyundai Elantra, Chevrolet Cruze, and Ford Focus (New York Daily News). The  market shares are Honda Civic , Toyota Corolla , Nissan Sentra , Hyundai Elantra , Chevrolet Cruze , and Ford Focus , with other small car models comprising the remaining . A sample of  compact car sales in Chicago showed the following number of vehicles sold.

Excel File: data12-27.xlsx

Honda Civic

98

Toyota Corolla

72

Nissan Sentra

54

Hyundai Elantra

44

Chevrolet Cruze

42

Ford Focus

25

Others

65

Use a goodness of fit test to determine whether the sample data indicate that the market shares for cars in Chicago are different than the market shares suggested by nationwide  sales. Using a  level of significance, what is the -value? Use Table 3 of Appendix B.

The -value is  .

What is your conclusion?

Conclude that the markets shares for the seven compact cars in Chicago   the market shares reported.

What market share differences, if any, exist in Chicago? Round your answers to three decimal places. Enter negative values as negative numbers.

Sample

Hypothesized

Compact Car

Market Share

Market Share

Difference

Honda Civic

 

-

=

 

Toyota Corolla

 

-

=

 

Nissan Sentra

 

-

=

 

Hyundai Elantra

 

-

=

 

Chevrolet Cruze

 

-

=

 

Ford Focus

 

-

=

 

Others

 

-

=

 



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Bara Research Group conducted a survey about church attendance. The survey respondents were asked about their church attendance and asked to indicate their age. Use the sample data to determine whether church attendance is independent of age. Using a  level of significance, what is the -value?

Excel File: data12-29.xlsx

Age

Church Attendance

20 to 29

30 to 39

40 to 49

50 to 59

Yes

31

63

94

72

No

69

87

106

78

Use Table 3 of Appendix B to find the -value.

The -value is  .

What is your conclusion?

Conclude church attendance is   of age.

What conclusion can you draw about church attendance, as individuals grow older?

Church attendance   as individuals grow older.



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In a  study, Phoenix Marketing International identified Bridgeport, Connecticut; San Jose, California; Washington, DC; and Lexington Park, Maryland, as the four U.S. cities with the highest percentage of millionaires (Kiplinger website). Consider a sample of data that show the following number of millionaires for samples of individuals from each of the four cities.

 

City

Bridgeport,

San Jose,

Washington,

Lexington Park,

Millionaire

CT

CA

D.C.

MD

Yes

44

34

35

36

No

456

266

365

364

a. What is the estimate of the percentage of millionaires in each of these cities (to 1 decimal)?

Bridgeport,

San Jose,

Washington,

Lexington Park,

CT

CA

D.C.

MD

Percentage, 

 

 

 

 

b. Using  level of significance, test for the equality of the population proportion of millionaires for these four cities. What is the -value?

Compute the value of the  test statistic (to 3 decimals).

 

Use Table 3 of Appendix B to find the -value.

The -value is  

What is your conclusion?

  that there is a difference among the population proportion of millionaires for these four cities.



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Is there any difference in the variability in golf scores for players on the LPGA Tour (the women's professional golf tour) and players on the PGA Tour (the men's professional golf tour)? A sample of  tournament scores from LPGA events showed a standard deviation of  strokes, and a sample of  tournament scores from PGA events showed a standard deviation of . Conduct a hypothesis test for equal population variances to determine whether there is any statistically significant difference in the variability of golf scores for male and female professional golfers. Use .

   
 
  

What is your conclusion?

There is   significant difference in the variances.

 



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