Question 1

The binomial experiment consists of n independent,identical trials,each of which results in either success or failure and is such that the probability of success on any trial is the same.

Accepted Answer

A) True 
 B)False

Question 2

According to data from the state blood program,40% of all individuals have group A blood.If six (6)individuals give blood,find the probability Find the mean number of individuals having group A blood.

Accepted Answer

A) 1.2 
B) 1.55 
C) 1.44 
D) 2.4

Question 3

The Post Office has established a record in a major Midwestern city for delivering 90% of its local mail the next working day.Of the eight,what is the average number you expect to be delivered the next day?

Accepted Answer

A) 3.6 
B) 4.0 
C) 7.2 
D) 2.7

Question 4

A large disaster cleaning company estimates that 30% of the jobs it bids on are finished within the bid time.Looking at a random sample of 8 jobs that is has contracted: Calculate the mean number of jobs completed within the bid time.

Accepted Answer

A) 4.0 
B) 2.4 
C) 2.0 
D) 5.6

Question 5

The probability that a given computer chip will fail is 0.02.Find the probability that of 5 delivered chips,exactly 2 will fail.

Accepted Answer

A) .9039 
B) .0922 
C) .0038 
D) .0000

Question 6

A Poisson random variable is a continuous variable that can be used to describe the number of occurrences of an event over a specified interval of time or space.

Accepted Answer

A) True 
 B)False

Question 7

According to data from the state blood program,40% of all individuals have group A blood.If six (6)individuals give blood,find the probability Exactly three of the individuals has group A blood?

Accepted Answer

A) .4000 
B) .2765 
C) .5875 
D) .0041

Question 8

A discrete variable that can often be used to describe the number of occurrences of an event over a specified interval of time or space is a _____ random variable.

Accepted Answer

A) Poisson 
B) Discrete 
C) Hypergeometric 
D) Continuous

Question 9

In a study conducted by UCLA,it was found that 25% of college freshmen support increased military spending.If 6 college freshmen are randomly selected,find the probability that: Only 1 support increased military spending

Accepted Answer

A) .0330 
B) .1318 
C) .3560 
D) .7844

Question 10

A car wash loses $30 on rainy days and makes $120 on days when it does not rain.If the probability of rain is 0.15,calculate the car wash's expected profit.

Accepted Answer

A) $90 
B) $76.50 
C) $106.50 
D) $97.50

Question 11

An insurance company will insure a $75,000 Hummer for its full value against theft at a premium of $1500 per year.Suppose that the probability that the Hummer will be stolen is 0.0075. Calculate the insurance company's expected net profit.

Accepted Answer

A) $937.50 
B) $551.25 
C) $1488.75 
D) $562.50

Question 12

According to a survey of adults,64% have money in a regular savings account.If we plan on surveying 50 randomly selected adults,find the mean number of adults who would have regular savings accounts.

Accepted Answer

A) 12 
B) 22 
C) 32 
D) 42

Question 13

A fair die is rolled 10 times.What is the average number of even number outcomes?

Accepted Answer

A) 3 
B) 4 
C) 5 
D) 6 
E) 7

Question 14

One die is thrown.What is the expected value of the number of dots on the top face of the die?

Accepted Answer

A) 1.0 
B) 3.5 
C) 4.0 
D) 3.0

Question 15

If the probability distribution of X is:  What is the expected value of X?

Accepted Answer

A) 1.0 
B) 5.0 
C) 2.25 
D) 2.24

Question 16

In a study conducted by UCLA,it was found that 25% of college freshmen support increased military spending.If 6 college freshmen are randomly selected,find the probability that: Fewer than 4 support increased military spending

Accepted Answer

A) .0330 
B) .7844 
C) .9624 
D) .9954

Question 17

The manager of the local grocery store has determined that,on the average,4 customers use the service desk every half-hour.Assume that the number of customers using the service desk has a Poisson distribution. What is the probability that during a randomly selected half-hour period no more than 2 customers use the service desk?

Accepted Answer

A) .2381 
B) .1465 
C) .7619 
D) .8535 
E) .0916

Question 18

An important part of the customer service responsibilities of a cable company relates to the speed with which trouble in service can be repaired.Historically,the data show that the likelihood is 0.75 that troubles in a residential service can be repaired on the same day.For the first five troubles reported on a given day,what is the probability that: Find the mean number of troubles repaired on the same day.

Accepted Answer

A) 3.75 
B) 0.94 
C) 1.94 
D) 2.50

Question 19

In the most recent election,19% of all eligible college students voted.If a random sample of 20 students were surveyed: Find the probability that exactly half voted in the election.

Accepted Answer

A) .0000 
B) .0014 
C) .0148 
D) .4997

Question 20

The Post Office has established a record in a major Midwestern city for delivering 90% of its local mail the next working day when there are 8 local letters mailed .What is the probability that the number of delivered will be within 2 standard deviations of the mean?

Accepted Answer

A) .9950 
B) .9619 
C) .8131 
D) .9996

Exam 5: Discrete Random Variables