Question 1

The normal distribution is a good approximation to the binomial if n ≥ 30.

Accepted Answer

A) True 
 B)False

Question 2

In a continuous distribution,

Accepted Answer

A) P(X < 5)is the same as P(X ≤ 5). 
B) P(X < 5)is less than P(X ≤ 5). 
C) P(X < 5)is more than P(X ≤ 5).

Question 3

Excel's = 100*RAND()function produces continuous random numbers that are uniformly distributed between 0 and 100.The standard deviation of this distribution is approximately

Accepted Answer

A) 50.00 
B) 28.87 
C) 33.33 
D) 25.00

Question 4

Any normal distribution has a mean of 0 and a standard deviation of 1.

Accepted Answer

A) True 
 B)False

Question 5

The time required for a citizen to complete the 2010 U.S.Census "long" form is normally distributed with a mean of 40 minutes and a standard deviation of 10 minutes.The slowest 10 percent of the citizens would need at least how many minutes to complete the form?

Accepted Answer

A) 27.2 
B) 35.8 
C) 52.8 
D) 59.6

Question 6

The true proportion of accounts receivable with some kind of error is 4 percent for Venal Enterprises.If an auditor randomly samples 50 accounts receivable,it is acceptable to use the normal approximation to estimate the probability that fewer than two will contain errors.

Accepted Answer

A) True 
 B)False

Question 7

A certain assembly line at Vexing Manufacturing Company averages 30 minutes between breakdowns.The median time between breakdowns is

Accepted Answer

A) 30.0 minutes. 
B) 35.7 minutes. 
C) 25.4 minutes. 
D) 20.8 minutes.

Question 8

The random variable X is normally distributed with mean of 80 and variance of 36.The 67th percentile of the distribution is

Accepted Answer

A) 72.00 
B) 95.84 
C) 90.00 
D) 82.64

Question 9

A random variable X is best described by a continuous uniform distribution from 20 to 45 inclusive.What is P(30 ≤ X ≤ 40)?

Accepted Answer

A) 0.20 
B) 0.40 
C) 0.60 
D) 0.80

Question 10

If arrivals follow a Poisson distribution with mean 1.2 arrivals per minute,find the 75th percentile of waiting times until the next arrival (i.e. ,75 percent below).

Accepted Answer

A) 1.155 minutes (69.3 seconds) 
B) 0.240 minute (14.4 seconds) 
C) 1.919 minutes (115.1 seconds)

Question 11

Excel's = RAND()function produces random numbers that are uniformly distributed from 0 to 1.What is the probability that the random number exceeds 0.75?

Accepted Answer

A) 75 percent 
B) 50 percent 
C) 25 percent

Question 12

If adult male heights are normally distributed with a mean of 180 cm and a standard deviation of 7 cm,how high should an aircraft lavatory door be to ensure that 99.9 percent of adult males will not have to stoop as they enter?

Accepted Answer

A) 195.7 cm 
B) 201.6 cm 
C) 207.3 cm 
D) 201.4 cm

Question 13

A letter is mailed to a sample of 500 homeowners.Based on past experience,the probability of an undeliverable letter is 0.06.The normal approximation to the binomial probability of 40 or more undeliverable letters is

Accepted Answer

A) 0.9632 
B) 0.0368 
C) 0.2305 
D) 0.7695

Question 14

The area under a normal curve is 1 only if the distribution is standardized N(0,1).

Accepted Answer

A) True 
 B)False

Question 15

The probability is 0.80 that a standard normal random variable is between −z and +z.The value of z is approximately

Accepted Answer

A) 1.28 
B) 1.35 
C) 1.96 
D) 1.45

Question 16

Which model best describes your waiting time until you get the next nonworking web URL ("This page cannot be displayed")as you click on various websites for Florida condo rentals?

Accepted Answer

A) Standard normal 
B) Uniform 
C) Normal 
D) Exponential

Question 17

If arrivals occur at a mean rate of 1.6 events per minute,the exponential probability of waiting less than 1 minute for the next arrival is

Accepted Answer

A) 0.2019 
B) 0.7104 
C) 0.8812 
D) 0.7981

Question 18

The exponential distribution is continuous and the Poisson distribution is discrete,yet the two distributions are closely related.

Accepted Answer

A) True 
 B)False

Question 19

A continuous uniform distribution is always symmetric.

Accepted Answer

A) True 
 B)False

Question 20

In Melanie's Styling Salon,the time to complete a simple haircut is normally distributed with a mean of 25 minutes and a standard deviation of 4 minutes.For a simple haircut,the middle 90 percent of the customers will require

Accepted Answer

A) between 18.4 and 31.6 minutes. 
B) between 19.9 and 30.1 minutes. 
C) between 20.0 and 30.0 minutes. 
D) between 17.2 and 32.8 minutes.

Exam 7: Continuous Probability Distributions

The normal distribution is a good approximation to the binomial if n ≥ 30.

In a continuous distribution,

Excel's = 100*RAND() function produces continuous random numbers that are uniformly distributed between 0 and 100.The standard deviation of this distribution is approximately

Any normal distribution has a mean of 0 and a standard deviation of 1.

The time required for a citizen to complete the 2010 U.S.Census "long" form is normally distributed with a mean of 40 minutes and a standard deviation of 10 minutes.The slowest 10 percent of the citizens would need at least how many minutes to complete the form?

The true proportion of accounts receivable with some kind of error is 4 percent for Venal Enterprises.If an auditor randomly samples 50 accounts receivable,it is acceptable to use the normal approximation to estimate the probability that fewer than two will contain errors.

A certain assembly line at Vexing Manufacturing Company averages 30 minutes between breakdowns.The median time between breakdowns is

The random variable X is normally distributed with mean of 80 and variance of 36.The 67th percentile of the distribution is

A random variable X is best described by a continuous uniform distribution from 20 to 45 inclusive.What is P(30 ≤ X ≤ 40) ?

If arrivals follow a Poisson distribution with mean 1.2 arrivals per minute,find the 75th percentile of waiting times until the next arrival (i.e. ,75 percent below) .

Excel's = RAND() function produces random numbers that are uniformly distributed from 0 to 1.What is the probability that the random number exceeds 0.75?

If adult male heights are normally distributed with a mean of 180 cm and a standard deviation of 7 cm,how high should an aircraft lavatory door be to ensure that 99.9 percent of adult males will not have to stoop as they enter?

A letter is mailed to a sample of 500 homeowners.Based on past experience,the probability of an undeliverable letter is 0.06.The normal approximation to the binomial probability of 40 or more undeliverable letters is

The area under a normal curve is 1 only if the distribution is standardized N(0,1).

The probability is 0.80 that a standard normal random variable is between −z and +z.The value of z is approximately

Which model best describes your waiting time until you get the next nonworking web URL ("This page cannot be displayed") as you click on various websites for Florida condo rentals?

If arrivals occur at a mean rate of 1.6 events per minute,the exponential probability of waiting less than 1 minute for the next arrival is

The exponential distribution is continuous and the Poisson distribution is discrete,yet the two distributions are closely related.

A continuous uniform distribution is always symmetric.

In Melanie's Styling Salon,the time to complete a simple haircut is normally distributed with a mean of 25 minutes and a standard deviation of 4 minutes.For a simple haircut,the middle 90 percent of the customers will require