Question 1

According to geologists, the San Francisco Bay Area experiences five earthquakes with a magnitude of 6.5 or greater every 100 years. What is the probability that more than two earthquakes with a magnitude of 6.5 or greater will strike the San Francisco Bay Area in the next 40 years?

Accepted Answer

A)  0.1353 
B)  0.2706 
C)  0.3233 
D)  0.8754

Question 2

It is known that 10% of the calculators shipped from a particular factory are defective. What is the probability that no more than one in a random sample of four calculators is defective?

Accepted Answer

A)  0.2916 
B)  0.3439 
C)  0.6561 
D)  0.9477

Question 3

According to a study by the Centers for Disease Control and Prevention, about 33% of U.S. births are Caesarean deliveries. Suppose seven expectant mothers are randomly selected. What is the standard deviation of the number of mothers who will have a Caesarean delivery?

Accepted Answer

A)  1.24 
B)  1.54 
C)  2.31 
D)  4.69

Question 4

Thirty percent of the CFA candidates have a degree in economics. A random sample of three CFA candidates is selected. What is the probability that at least one of them has a degree in economics?

Accepted Answer

A)  0.300 
B)  0.343 
C)  0.657 
D)  0.900

Question 5

An urn contains 12 balls, five of which are red. The selection of a red ball is desired and is therefore considered to be a success. If a person draws three balls from the urn, what is the probability of two successes?

Accepted Answer

A)  0.1591 
B)  0.3182 
C)  0.6810 
D)  0.8409

Question 6

Consider the following probability distribution.  The variance is ________.

Accepted Answer

A)  1.14 
B)  1.29 
C)  1.65 
D)  1.94

Question 7

Which of the following can be represented by a continuous random variable?

Accepted Answer

A)  The average temperature in Tampa, Florida, during the month of July 
B)  The number of typos found on a randomly selected page of this test bank 
C)  The number of students who will get financial assistance in a group of 50 randomly selected students 
D)  The number of customers who visit a department store between 10:00 a.m. and 11:00 a.m. on Mondays

Question 8

On a particular production line, the likelihood that a light bulb is defective is 5%. Ten light bulbs are randomly selected. What are the mean and variance of the number of defective bulbs?

Accepted Answer

A)  0.475 and 0.475 
B)  0.475 and 0.6892 
C)  0.50 and 0.475 
D)  0.50 and 0.6892

Question 9

According to the Department of Transportation, 27% of domestic flights were delayed in the last year at JFK airport. Five flights are randomly selected at JFK. What is the probability that all five flights are on time?

Accepted Answer

A)  0.1513 
B)  0.7927 
C)  0.8487 
D)  0.2073

Question 10

A bank manager estimates that an average of two customers enters the tellers' queue every five minutes. Assume that the number of customers that enters the tellers' queue is Poisson distributed. What is the probability that at least two customers enter the queue in a randomly selected five-minute period?

Accepted Answer

A)  0.1353 
B)  0.2707 
C)  0.4060 
D)  0.5940

Question 11

Consider the following discrete probability distribution.  What is the probability that X is less than 5?

Accepted Answer

A)  0.10 
B)  0.15 
C)  0.35 
D)  0.45

Question 12

Assume that the mean success rate of a Poisson process is six successes per hour.
A) Find the expected number of successes in a 40-minute period.
B) Find the expected number of successes in a three-hour period.
C) Find the probability of at least two successes in a 30-minute period.

Accepted Answer

The answer of Assume that the mean success rate of...

Question 13

Chauncey Billups, a current shooting guard for the Los Angeles Clippers, has a career free-throw percentage of 89.4%. Suppose he shoots six free throws in tonight's game. What is the standard deviation of the number of free throws that Billups will make?

Accepted Answer

A)  0.5364 
B)  0.5686 
C)  0.7540 
D)  5.6860

Question 14

The following table shows the number of students who did not attend statistics class over the 35 class meetings last semester.  What is the expected number of absent students per class for the next semester?

Accepted Answer

A)  2.123 
B)  1.857 
C)  1.965 
D)  1.246

Question 15

According to the Department of Transportation, 27% of domestic flights were delayed in the last year at JFK airport. Five flights are randomly selected at JFK. What is the probability that all five flights are delayed?

Accepted Answer

A)  0.0194 
B)  0.0208 
C)  0.0014 
D)  0.0222

Question 16

Given two random variables X and Y, the expected value of their sum, E (X + Y), is equal to the sum of their individual expected values, E (X) and E (Y).

Accepted Answer

A) True 
 B)False

Question 17

The Excel's function HYPERGEOM.DIST can be used to solve hypergeometric probabilities.

Accepted Answer

A) True 
 B)False

Question 18

The foreclosure crisis has been particularly devastating in housing markets in much of the south and west United States, but even when analysis is restricted to relatively strong housing markets the numbers are staggering. For example, in 2017 an average of three residential properties were auctioned off each weekday in the city of Boston, up from an average of one per week in 2011. What is the probability that exactly 10 foreclosure auctions occurred during a randomly selected five-day week in 2017 in Boston?

Accepted Answer

A)  0.0008 
B)  0.0486 
C)  0.1185 
D)  0.9514

Exam 5: Discrete Probability Distributions