Question 1:

A major U.S. automaker has evaluated that the city mileage for one of its new SUV models is normally distributed with a mean equal to 15.2 mpg. A report issued by the company shown that 22 percent of the SUV model vehicles will get more than 17 mpg in the city. Provide this information, what is the city mileage standard deviation for this SUV model?

Answer
0.77 mpg
Approximately 2.34 mpg
1.8 mpg
Approximately 3.1 mpg

Question 2 :

A major cell phone service provider has evaluated that the number of minutes that its customers use their phone per month is normally distributed with a mean equal to 445.5 minutes with a standard deviation equal to 177.8 minutes. As a promotion, the company plans to hold a drawing to give away one free vacation to Hawaii for a customer who uses between 400 and 402 minutes during a particular month. Based on the information provided, what proportion of the company's customers would be eligible for the drawing?

Answer
Approximately 0.1026
About 0.004
Approximately 0.2013
About 0.02

Question 3:

A major cell phone service provider has evaluate that the number of minutes that its customers use their phone per month is normally distributed with a mean equal to 445.5 minutes with a standard deviation equal to 177.8 minutes. The company is thinking of changing its fee structure so that anyone who uses the phone less than 250 minutes during a given month will pay a reduced monthly fee. Based on the available information, what percentage of current customers would be eligible for the reduced fee?

Answer
About 36.4 percent
Approximately 52 percent
About 86.6 percent
About 13.6 percent

Question 4

A major cell phone service provider has determined that the number of minutes that its customers use their phone per month is normally distributed with a mean equal to 445.5 minutes with a standard deviation equal to 177.8 minutes. The company is thinking of charging a lower rate for customers who use the phone less than a specified amount. If it wishes to give the rate reduction to no more than 12 percent of its customers, what should the cut-off be?

Answer
About 237 minutes
About 654 minutes
About 390 minutes
About 325 minutes

Question 5

A professor noted that the grades of his students were normally distributed with a mean of 75.07 and a standard deviation of 11.65. If only 10 percent of the students received grades of A, what is the minimum score needed to receive an A?

Answer
80.00
85.00
90.00
95.00

Question 6

A recent study showed that the length of time that juries deliberate on a verdict for civil trials is normally distributed with a mean equal to 12.56 hours with a standard deviation of 6.7 hours. Given this information, what is the probability that a deliberation will last between 10 and 15 hours?

Answer
Approximately 0.29
Nearly 0.75
About 0.48
About 0.68

Question 7

Employees at a large computer company earn sick leave in one-minute increments depending on how many hours per month they work. They can then use the sick leave time any time throughout the year. Any unused time goes into a sick bank account that they or other employees can use in the case of emergencies. The human resources department has determined that the amount of unused sick time for individual employees is uniformly distributed between 0 and 480 minutes. Based on this information, what is the probability that an employee will have less than 20 minutes of unused sick time?

Answer
0.002
0.966
0.063
0.042

Question 8

Employees at a large computer company earn sick leave in one-minute increments depending on how many hours per month they work. They can then use the sick leave time any time throughout the year. Any unused time goes into a sick bank account that they or other employees can use in the case of emergencies. The human resources department has determined that the amount of unused sick time for individual employees is uniformly distributed between 0 and 480 minutes. Based on this information, what is the probability that three randomly chosen employees have over 400 unused sick minutes at the end of the year?

0.1667
0.0046
0.5001
0.0300

Question 9

Employees at a large computer company earn sick leave in one-minute increments depending on how many hours per month they work. They can then use the sick leave time any time throughout the year. Any unused time goes into a sick bank account that they or other employees can use in the case of emergencies. The human resources department has determined that the amount of unused sick time for individual employees is uniformly distributed between 0 and 480 minutes. The company has decided to give a cash payment to any employee that returns over 400 minutes of sick leave at the end of the year. What percentage of employees could expect a cash payment?

Answer
16.67 percent
0.1667 percent
Just over 43 percent
80 percent
1 points

Question 10

Employees at a large computer company earn sick leave in one-minute increments depending on how many hours per month they work. They can then use the sick leave time any time throughout the year. Any unused time goes into a sick bank account that they or other employees can use in the case of emergencies. The human resources department has determined that the amount of unused sick time for individual employees is uniformly distributed between 0 and 480 minutes. The company has decided to give a cash payment to any employee that returns over a specified amount of sick leave minutes. Assuming that the company wishes no more than 5 percent of all employees to get a cash payment, what should the required number of minutes be?

Answer
24 minutes
419 minutes
456 minutes
470 minutes

Question 11

It is assumed that the time customers spend in a record store is uniformly distributed between 3 and 12 minutes. Based on this information, what is the probability that a customer will be exactly 7.50 minutes in the record store?

Answer
0.1250
0.05
Essentially zero
0.111

Question 12

It is assumed that the time customers spend in a record store is uniformly distributed between 3 and 12 minutes. Based on this information, what is the probability that a customer will spend more than 9 minutes in the record store?

Answer
0.33
0.1111
0.67
0.25

Question 13

It is assumed that the time failures for an electronic component are exponentially distributed with a mean of 50 hours between consecutive failures. Based on this information, what is the probability that a randomly selected part will fail in less than 10 hours?

Answer
About 0.82
About 0.20
About 0.33
About 0.18

Question 14

It is assumed that the time failures for an electronic component are exponentially distributed with a mean of 50 hours between consecutive failures. If one extra component is installed as a backup, what is the probability of at least one of the two components working for at least 60 hours?

Answer
About 0.51
About 0.09
About 0.06
About 0.70

Question 15

It is assumed that the time failures for an electronic component are exponentially distributed with a mean of 50 hours between consecutive failures. What is the probability that a component will be functioning after 60 hours?

Answer
Approximately 0.30
About 0.70
About 0.21
About 0.49

Question 16

It is thought that the time between customer arrivals at a fast food business is exponentially distributed with equal to 5 customers per hour. Given this information, what is the mean time between arrivals?

Answer
12 minutes
5 minutes
5 hours
2 minutes

Question 17

Students who have completed a speed reading course have reading speeds that are normally distributed with a mean of 950 words per minute and a standard deviation equal to 220 words per minute. Based on this information, what is the probability of a student reading at more than 1400 words per minute after finishing the course?

Answer
0.0202
0.5207
0.4798
0.9798

Question 18

Students who have completed a speed reading course have reading speeds that are normally distributed with a mean of 950 words per minute and a standard deviation equal to 220 words per minute. If two students were selected at random, what is the probability that they would both read at less than 400 words per minute?

Answer
0.4938
0.0062
0.00004
0.2438

Question 19

Suppose that it is believed that investor returns on equity investments at a particular brokerage house are normally distributed with a mean of 9 percent and a standard deviation equal to 3.2 percent. What percent of investors at this brokerage hour earned at least 5 percent?

Answer
89.44 percent
10.56 percent
39.44 percent
100 percent

Question 20

The makers of Sweet-Things candy sell their candy by the box. Based on company policy, the mean target weight of all boxes is 2.0 pounds. To make sure that they are not putting too much in the boxes, the manager wants no more than 3 percent of all boxes to contain more than 2.10 pounds of candy. In order to do this, what should the mean fill weight be set to if the fill standard deviation is 0.13 pounds? Assume that the box weights are normally distributed.

Answer
Just over 2 pounds
Approximately 2.33 pounds
Nearly 1.27 pounds
Approximately 1.86 pounds

Question 21

The makers of Sweet-Things candy sell their candy by the box. Based on company policy, the mean target weight of all boxes is 2.0 pounds. To make sure that they are not putting too much in the boxes, the manager wants no more than 3 percent of all boxes to contain more than 2.10 pounds of candy. In order to do this, with a mean weight of 2 pounds, what must the standard deviation be? Assume that the box weights are normally distributed.

Answer
Approximately 0.05 pounds
-0.133 pounds
1.144 pounds
None of these.

Question 22

The manager at a local movie theater has collected data for a long period of time and has concluded that the revenue from concession sales during the first show each evening is normally distributed with a mean equal to $336.25 and a standard deviation equal to $80. Based on this information, what are the chances that the revenue on the first show will be between $300 and $500?

Answer
About 0.3062
Approximately 0.6534
0.1736
Approximately 0.4798

Question 23

The manager at a local movie theater has collected data for a long period of time and has concluded that the revenue from concession sales during the first show each evening is normally distributed with a mean equal to $336.25 and a variance equal to 1,456. Based on this information, what are the chances that the revenue on the first show will exceed $800?

Answer
0.1255
Essentially zero
0.3745
0.9999

Question 24

The manager of a computer help desk operation has collected enough data to conclude that the distribution of time per call is normally distributed with a mean equal to 8.21 minutes and a standard deviation of 2.14 minutes. The manager has decided to have a signal system attached to the phone so that after a certain period of time, a sound will occur on her employees' phone if she exceeds the time limit. The manager wants to set the time limit at a level such that it will sound on only 8 percent of all calls. The time limit should be:

Answer
10.35 minutes.
approximately 5.19 minutes.
about 14.58 minutes.
about 11.23 minutes.

Question 25

The manager of a computer help desk operation has collected enough data to conclude that the distribution of time per call is normally distributed with a mean equal to 8.21 minutes and a standard deviation of 2.14 minutes. What is the probability that three randomly monitored calls will each be completed in 4 minutes or less?

Answer
0.4756
Approximately 0.1076
About 0.00001
Can't be determined without more information.

Question 26

The time between calls to an emergency 911-call center is exponentially distributed with a mean time between calls of 645 seconds. Based on this information, what is the probability that the time between the next two calls is between 200 and 400 seconds?

Answer
Approximately 0.47
About 0.199
About 0.747
About 0.801

Question 27

The transportation manager for the State of New Jersey has determined that the time between arrivals at a toll booth on the state's turnpike is exponentially distributed with = 4 cars per minute. Based on this information, the probability that it will take exactly 30 seconds between arrivals is:

Answer
0.0006
0
0.9994
0.25

Question 28

The transportation manager for the State of New Jersey has determined that the time between arrivals at a toll booth on the state's turnpike is exponentially distributed with = 4 cars per minute. Based on this information, what is the probability that the time between any two cars arriving will be less than half a minute?

Answer
Approximately 1.0
Approximately 0
about 0.86
About 0.75

Question 29

Which of the following is not a characteristic of the normal distribution?

Answer
Symmetric
Mean=median=mode
Bell-shaped
Equal probabilities at all values of x

Question 30

Which of the given probability distributions would most likely be used to describe the time between failures for electronic components?

Answer
Binomial distribution
Exponential distribution
Uniform distribution
Normal distribution