Question 1

The exponential distribution is a probability distribution for a random variable measured as a rate of an event occurring.

Accepted Answer

A) True 
 B)False

Question 2

Two business major students, in two different sections of an economics class, were comparing test scores. The following shows the sections' mean and standard deviation.  The student in section 2 scored 75. The student's z score would be _____.

Accepted Answer

The answer of Two business major students, in two different...

Question 3

The time to fly between New York City and Chicago is uniformly distributed with a minimum of 120 minutes and a maximum of 150 minutes. What is the distribution's standard deviation?

Accepted Answer

A)  8.66 minutes 
B)  75 minutes 
C)  135 minutes 
D)  270 minutes

Question 4

The mean score of a college entrance test is 500; the standard deviation is 75. The scores are normally distributed. What percent of the students scored below 320?

Accepted Answer

A)  About 50.82% 
B)  About 34.13% 
C)  About 7.86% 
D)  About 0.82%

Question 5

Some normal probability distributions are positively skewed.

Accepted Answer

A) True 
 B)False

Question 6

The weekly mean income of a group of executives is $1,000 and the standard deviation of this group is $100. The distribution is normal. What percent of the executives have an income of $925 or less?

Accepted Answer

A)  About 15% 
B)  About 85% 
C)  About 50% 
D)  About 23%

Question 7

From past history, the scores on a statistics test are normally distributed with a mean score of 70 and a standard deviation of 5. To earn a "C" on the test, a student must be in the top 25% of the class. A student would need to score at least ______ to receive a "C" grade.

Accepted Answer

The answer of From past history, the scores on a...

Question 8

A major credit card company has determined that customers charge between $100 and $1,100 per month. If the monthly amount charged is uniformly distributed, the average charge would be ______.

Accepted Answer

The answer of A major credit card company has determined...

Question 9

What is an important similarity between the uniform and normal probability distributions?

Accepted Answer

A)  The mean, median, and mode are all equal. 
B)  The mean and median are equal. 
C)  They are negatively skewed. 
D)  About 68% of all observations are within one standard deviation of the mean.

Question 10

The proportion of the area under a normal curve that is to the right of z = -1.21 is _______.

Accepted Answer

The answer of The proportion of the area under a...

Question 11

After arriving at the university student medical clinic, the waiting times to receive service after checking-in follow an exponential distribution with a mean of 10 minutes. Calculate the probability a student waits more than 12 minutes.

Accepted Answer

The answer of After arriving at the university student medical...

Question 12

The standard normal probability distribution is unique because it has _________.

Accepted Answer

A)  A mean of 1 and any standard deviation 
B)  Any mean and a standard deviation of 1 
C)  A mean of 0 and any standard deviation 
D)  A mean of 0 and a standard deviation of 1

Question 13

If an average of 12 customers is served per hour, what is the probability that the next customer will arrive in 3 minutes or less?

Accepted Answer

A)  0.55 
B)  0.30 
C)  0.45 
D)  0.39

Question 14

Describe the normal distribution.

Accepted Answer

The answer of Describe the normal distribution....

Question 15

In the exponential distribution, the mean and standard deviation are equal to ______________.

Accepted Answer

The answer of In the exponential distribution, the mean and...

Question 16

For a standard normal distribution, what is the probability that z is greater than 1.75?

Accepted Answer

A)  0.0401 
B)  0.0459 
C)  0.4599 
D)  0.9599

Question 17

In a uniform distribution, with a minimum, a, and maximum, b, the probability that the random variable, x, is between a and (b - a)/2 is ___________.

Accepted Answer

The answer of In a uniform distribution, with a minimum,...

Question 18

The annual commissions per salesperson employed by a retailer of mobile communication devices averaged $40,000, with a standard deviation of $5,000. What percent of the salespersons earn between $32,000 and $42,000?

Accepted Answer

A)  60.06% 
B)  39.94% 
C)  34.13% 
D)  81.66%

Question 19

If an average of 12 customers is served per hour, what is the probability that the next customer will arrive in 6 minutes or less?

Accepted Answer

A)  0.61 
B)  0.30 
C)  0.70 
D)  0.39

Question 20

After arriving at the university student medical clinic, the waiting times to receive service after checking-in follow an exponential distribution with a mean of 10 minutes. How many students are served per hour?

Accepted Answer