Week 2 Quizes's

 

For a standard normal distribution, the probability of obtaining a z value of less than 1.6 is
	1.6
			0.945201
The assembly time for a product is uniformly distributed between 6 and 10 minutes. The probability of assembling the product in 7 minutes or more is _____.
	10	10
	6	7
	4	3		0.75
Assume z is a standard normal random variable. Then P(–1.96 ≤ z ≤ –1.6) equals _____.
			-1.96		0.024998
			-1.5		0.066807		0.041809
Consider the following.
f(x) = (1/19) e -x/19               x ≥ 0
The probability that x is between 7 and 9 is
		19
		0.05
			7	0.308174
			9	0.377296	0.069122
The starting salaries of individuals with an MBA degree are normally distributed with a mean of $40,000 and a standard deviation of $5,000.
Refer to Exhibit 6-4. What is the probability that a randomly selected individual with an MBA degree will get a starting salary of at least $30,000?
			40000
			5000			-2	0.02275
			30000
						P(Z>-2	0.97725
Consider the following.
f(x) = (1/8) e -x/8               x ≥ 0
The mean of x is _____.
	8
Suppose x is a normally distributed random variable with a mean of 5 and a variance of 4. The probability that x is greater than 10.52 is _____.
		mean	5
		variance	4
		10.52
			2.76	0.99711
			P(Z>2.76)	0.0029
Consider the continuous random variable x, which has a uniform distribution over the interval from 20 to 28.
Refer to Exhibit 6-1. The probability that x will take on a value between 21 and 25 is_____.
		20		21
		28		25
			8		4		0.5
Exhibit 6-2
The travel time for a college student traveling between her home and her college is uniformly distributed between 40 and 90 minutes.
Refer to Exhibit 6-2. The probability that she will finish her trip in 80 minutes or less is _____.
			40		40
			90		80
				50		40		0.8
The travel time for a college student traveling between her home and her college is uniformly distributed between 50 and 80 minutes. The probability that she will finish her trip in 60 minutes or less is _____.
			50		50
			80		60
				30		10		0.333333
Given that z is a standard normal random variable, what is the value of z if the area to the right of z is .1112?
		0
				0.5
The weight of items produced by a machine is normally distributed with a mean of 9 ounces and a standard deviation of 3 ounces. What is the probability that a randomly selected item will weigh more than 12 ounces?
			mean	9
			variance	3
			12
				1	0.841345
				P(Z>2.76)	0.1587
The assembly time for a product is uniformly distributed between 6 and 8 minutes. The probability density function has what value in the interval between 6 and 8?
			6
			8
					0.5
Consider the continuous random variable x, which has a uniform distribution over the interval from 40 to 48. The variance of x is approximately _____.
				40
				48	8	64
						5.333333
The life expectancy of a particular brand of tire is normally distributed with a mean of 30,000 and a standard deviation of 6,000 miles. What percentage of tires will have a life of 21,600 to 38,400 miles?
					mean	30000				mean	30000
					variance	6000				variance	6000
					21600					38400
						-1.4	0.080757				1.4	0.919243		83.85%
						P(Z>2.76)	0.9192				P(Z>2.76)	0.0808
Exhibit 6-5
The weight of items produced by a machine is normally distributed with a mean of 8 ounces and a standard deviation of 2 ounces.
Refer to Exhibit 6-5. What is the probability that a randomly selected item will weigh between 11 and 12 ounces?
				mean	8				mean	8
				variance	2				variance	2
				11					12
					1.5	0.933193				2	0.97725		0.0441
					P(Z>2.76)	0.0668				P(Z>2.76)	0.0228		0.9104
Assume z is a standard normal random variable. Then P(z ≥ 2.11) equals _____.
			2.11	0.982571
				0.017429
Exhibit 6-7
f(x) = (1/10) e-x/10               x ≥ 0
Refer to Exhibit 6-7. The probability that x is between 3 and 6 is _____.
		10
		0.10
			3	0.259182
			6	0.451188	0.192007
The assembly time for a product is uniformly distributed between 6 and 11 minutes. The probability of assembling the product in 7 to 9 minutes is _____.
			6		7
			11		9
				5		2		0.4
Exhibit 6-4
The starting salaries of individuals with an MBA degree are normally distributed with a mean of $40,000 and a standard deviation of $5,000.
Refer to Exhibit 6-4. What percentage of MBAs will have starting salaries of $34,000 to $46,000?
			mean	40000				mean	40000
			STD	5000				STD	5000
			34000					46000
				-1.2	0.11507				1.2	0.88493		0.7699	76.99%
				P(Z>2.76)	0.8849				P(Z>2.76)	0.1151		0.0000
Assume z is a standard normal random variable. What is the value of z if the area between –z and z is 0.8557?
				0.8611
				1.8611
				0.93055	1.48
Given that z is a standard normal random variable, what is the value of z if the area to the left of z is 0.9370?
		P(Z<z) =	0.937	1.530068
	right		0.063	-1.53007
The life expectancy of a particular brand of tire is normally distributed with a mean of 30,000 and a standard deviation of 6,000 miles. What is the probability that a randomly selected tire will have a life of at least 24,000 miles?
				mean	30000
				STD	6000
				24000
					-1	0.158655
					P(Z>-1)	0.8413
9
Exhibit 6-2
The travel time for a college student traveling between her home and her college is uniformly distributed between 40 and 90 minutes.
Refer to Exhibit 6-2. The probability that her trip will take longer than 60 minutes is _____.
				40		40
				90		60
					50		20		0.4
The travel time for a college student traveling between her home and her college is uniformly distributed between 30 and 70 minutes. The probability that her trip will take longer than 50 minutes is _____.
				30		30
				70		50
					40		20		0.5
Consider the following.
f(x) = (1/18) e -x/18               x ≥ 0
The probability that x is between 7 and 9 is _____.
		18
		0.06
			7	0.32219
			9	0.393469	0.071279
The assembly time for a product is uniformly distributed between 1 and 7 minutes. The standard deviation of assembly time (in minutes) is approximately _____.
			1
			7
					3
The weight of football players is normally distributed with a mean of 215 pounds and a standard deviation of 20 pounds. What percent of players weigh between 205 and 225 pounds?
			mean	215				mean	215
			STD	20				STD	20
			205					225
				-0.5	0.308538				0.5	0.691462		0.3829	38.29%
				P(Z>2.76)	0.6915				P(Z>2.76)	0.3085		0.0000
The assembly time for a product is uniformly distributed between 6 and 10 minutes. The probability of assembling the product in 7 to 9 minutes is _____.
				6		7
				10		9
					4		2		0.5
The weight of items produced by a machine is normally distributed with a mean of 9 ounces and a standard deviation of 2 ounces. What is the probability that a randomly selected item weighs exactly 9 ounces?
				mean	9
				variance	2
				9
					0	0.5
					P(Z>2.76)	0.5000
The starting salaries of individuals with an MBA degree are normally distributed with a mean of $35,000 and a standard deviation of $8,000. What is the probability that a randomly selected individual with an MBA degree will get a starting salary of at least $43,800?
				mean	35000
				STD	8000
				43800
					1.1	0.864334
					P(Z>-1)	0.1357
Assume z is a standard normal random variable. What is the value of z if the area to the right of z is 0.9911?
				P(Z<z) =	0.0089	-2.36975
			right		0.9911	2.369752
Suppose x is a normally distributed random variable with a mean of 5 and a variance of 4. The probability that x is greater than 10.52 is _____.
				mean	5
				STD	4
				10.52
					1.38	0.916207
					P(Z>-1)	0.0838
The travel time for a college student traveling between her home and her college is uniformly distributed between 60 and 90 minutes. The probability that she will finish her trip in 80 minutes or less is _____.
			60		60
			90		80
				30		20		0.666667
The weight of football players is normally distributed with a mean of 220 pounds and a standard deviation of 20 pounds. What is the minimum weight of the middle 95% of the players?
			220
			20
			0.95
			1.95
			0.975	1.959964
			Value =	259.2