Question 1

A discrete random variable:

Accepted Answer

A)  can be treated as continuous when it has a large range of values. 
B)  cannot be treated as continuous. 
C)  is best avoided if at all possible. 
D)  is usually uniformly distributed. 
A)  can be treated as continuous when it has a large range of values. 
B)  cannot be treated as continuous. 
C)  is best avoided if at all possible. 
D)  is usually uniformly distributed.

Question 2

The hypergeometric distribution assumes that the probability of a success remains the same from one trial to the next.

Accepted Answer

A) True 
 B)False

Question 3

The probability that a customer will use a stolen credit card to make a purchase at a certain Target store is 0.003.If 400 purchases are made in a given day,what is the approximate Poisson probability that 4 or fewer will be with stolen cards?

Accepted Answer

A)  .0053 
B)  .0076 
C)  .9923 
D)  .0555 
A)  .0053 
B)  .0076 
C)  .9923 
D)  .0555

Question 4

A network has three independent file servers,each with 90 percent reliability.The probability that the network will be functioning correctly (at least one server is working)at a given time is:

Accepted Answer

A)  99.9 percent. 
B)  97.2 percent. 
C)  95.9 percent. 
D)  72.9 percent. 
A)  99.9 percent. 
B)  97.2 percent. 
C)  95.9 percent. 
D)  72.9 percent.

Question 5

Which probability model would you use to describe the number of customers served at a certain California Pizza Kitchen until the first customer orders split pea soup?

Accepted Answer

A)  Binomial 
B)  Geometric 
C)  Uniform 
D)  Poisson 
A)  Binomial 
B)  Geometric 
C)  Uniform 
D)  Poisson

Question 6

On average,an IRS auditor discovers 4.7 fraudulent income tax returns per day.On a randomly chosen day,what is the probability that she discovers fewer than two?

Accepted Answer

A)  .0518 
B)  .0427 
C)  .1005 
D)  .1523 
A)  .0518 
B)  .0427 
C)  .1005 
D)  .1523

Question 7

The Poisson distribution can be skewed either left or right,depending on λ.

Accepted Answer

A) True 
 B)False

Question 8

At Ersatz University,the graduating class of 480 includes 96 guest students from Latvia.A sample of 10 students is selected at random to attend a dinner with the Board of Governors.Use the binomial model to obtain the approximate hypergeometric probability that the sample contains at least three Latvian students.

Accepted Answer

A)  .3222 
B)  .1209 
C)  .8791 
D)  .6778 
A)  .3222 
B)  .1209 
C)  .8791 
D)  .6778

Question 9

The discrete random variable X is the number of students that show up for Professor Smith's office hours on Monday afternoons.The table below shows the probability distribution for X.What is the expected value E(X)for this distribution?

Accepted Answer

A)  1.2 
B)  1.0 
C)  1.5 
D)  2.0 
A)  1.2 
B)  1.0 
C)  1.5 
D)  2.0

Question 10

A discrete binomial distribution is skewed right when π > .50.

Accepted Answer

A) True 
 B)False

Question 11

The standard deviation of a Poisson random variable is the square root of its mean.

Accepted Answer

A) True 
 B)False

Question 12

Which is a not a discrete random variable?

Accepted Answer

A)  The number of births in a hospital on a given day 
B)  The number of fives obtained in four rolls of a die 
C)  The hourly earnings of a call center employee in Boston 
D)  The number of applicants applying for a civil service job 
A)  The number of births in a hospital on a given day 
B)  The number of fives obtained in four rolls of a die 
C)  The hourly earnings of a call center employee in Boston 
D)  The number of applicants applying for a civil service job

Question 13

Historically,2 percent of the stray dogs in Southfield are unlicensed.On a randomly chosen day,the Southfield city animal control officer picks up seven stray dogs.What is the probability that fewer than two will be unlicensed?

Accepted Answer

A)  .8681 
B)  .9921 
C)  .3670 
D)  .0076 
A)  .8681 
B)  .9921 
C)  .3670 
D)  .0076

Question 14

If 5 percent of automobiles in Oakland County have one burned-out headlight,what is the probability that,in a sample of 10 automobiles,none will have a burned-out headlight?

Accepted Answer

A)  .5987 
B)  .3151 
C)  .0116 
D)  .1872 
A)  .5987 
B)  .3151 
C)  .0116 
D)  .1872

Question 15

The probability that a ticket holder will miss a flight is .005.If 180 passengers take the flight,what is the approximate Poisson probability that at least 2 will miss the flight?

Accepted Answer

A)  .9372 
B)  .0628 
C)  .1647 
D)  .2275 
A)  .9372 
B)  .0628 
C)  .1647 
D)  .2275

Question 16

Which model best describes the number of incorrect fare quotations by a well-trained airline ticket agent between 2 p.m.and 3 p.m.on a particular Thursday.

Accepted Answer

A)  Binomial 
B)  Poisson 
C)  Hypergeometric 
D)  Geometric 
A)  Binomial 
B)  Poisson 
C)  Hypergeometric 
D)  Geometric

Question 17

When you send out a resume,the probability of being called for an interview is .20.What is the probability that you get your first interview within the first five resumes that you send out?

Accepted Answer

A)  .6723 
B)  .1024 
C)  .2410 
D)  .0016 
A)  .6723 
B)  .1024 
C)  .2410 
D)  .0016

Question 18

The random variable X is the number of shots it takes before you make the first free throw in basketball.Assuming the probability of success (making a free throw)is constant from trial to trial,what type of distribution does X follow?

Accepted Answer

A)  Binomial 
B)  Poisson 
C)  Hypergeometric 
D)  Geometric 
A)  Binomial 
B)  Poisson 
C)  Hypergeometric 
D)  Geometric

Question 19

A discrete random variable has a countable number of distinct values.

Accepted Answer

A) True 
 B)False

Question 20

Jankord Jewelers permits the return of their diamond wedding rings,provided the return occurs within two weeks.Typically,10 percent are returned.If eight rings are sold today,what is the probability that fewer than three will be returned?

Accepted Answer

A)  .9950 
B)  .9619 
C)  .0331 
D)  .1488 
A)  .9950 
B)  .9619 
C)  .0331 
D)  .1488

A discrete random variable:

The hypergeometric distribution assumes that the probability of a success remains the same from one trial to the next.

The probability that a customer will use a stolen credit card to make a purchase at a certain Target store is 0.003.If 400 purchases are made in a given day,what is the approximate Poisson probability that 4 or fewer will be with stolen cards?

A network has three independent file servers,each with 90 percent reliability.The probability that the network will be functioning correctly (at least one server is working)at a given time is:

Which probability model would you use to describe the number of customers served at a certain California Pizza Kitchen until the first customer orders split pea soup?

On average,an IRS auditor discovers 4.7 fraudulent income tax returns per day.On a randomly chosen day,what is the probability that she discovers fewer than two?

The Poisson distribution can be skewed either left or right,depending on λ.

The discrete random variable X is the number of students that show up for Professor Smith's office hours on Monday afternoons.The table below shows the probability distribution for X.What is the expected value E(X)for this distribution?

A discrete binomial distribution is skewed right when π > .50.

The standard deviation of a Poisson random variable is the square root of its mean.

Which is a not a discrete random variable?

Historically,2 percent of the stray dogs in Southfield are unlicensed.On a randomly chosen day,the Southfield city animal control officer picks up seven stray dogs.What is the probability that fewer than two will be unlicensed?

If 5 percent of automobiles in Oakland County have one burned-out headlight,what is the probability that,in a sample of 10 automobiles,none will have a burned-out headlight?

The probability that a ticket holder will miss a flight is .005.If 180 passengers take the flight,what is the approximate Poisson probability that at least 2 will miss the flight?

Which model best describes the number of incorrect fare quotations by a well-trained airline ticket agent between 2 p.m.and 3 p.m.on a particular Thursday.

When you send out a resume,the probability of being called for an interview is .20.What is the probability that you get your first interview within the first five resumes that you send out?

The random variable X is the number of shots it takes before you make the first free throw in basketball.Assuming the probability of success (making a free throw)is constant from trial to trial,what type of distribution does X follow?

A discrete random variable has a countable number of distinct values.

Jankord Jewelers permits the return of their diamond wedding rings,provided the return occurs within two weeks.Typically,10 percent are returned.If eight rings are sold today,what is the probability that fewer than three will be returned?

Overview of Statistics

Data Collection

Describing Data Visually

Descriptive Statistics

Probability

Continuous Probability Distributions

Sampling Distributions and Estimation

One-Sample Hypothesis Tests

Two-Sample Hypothesis Tests

Analysis of Variance

Simple Regression

Multiple Regression

Time-Series Analysis

Chi-Square Tests

Nonparametric Tests

Quality Management

Filters

Exam 6: Discrete Probability Distributions

A discrete random variable:

The hypergeometric distribution assumes that the probability of a success remains the same from one trial to the next.

The probability that a customer will use a stolen credit card to make a purchase at a certain Target store is 0.003.If 400 purchases are made in a given day,what is the approximate Poisson probability that 4 or fewer will be with stolen cards?

A network has three independent file servers,each with 90 percent reliability.The probability that the network will be functioning correctly (at least one server is working)at a given time is:

Which probability model would you use to describe the number of customers served at a certain California Pizza Kitchen until the first customer orders split pea soup?

On average,an IRS auditor discovers 4.7 fraudulent income tax returns per day.On a randomly chosen day,what is the probability that she discovers fewer than two?

The Poisson distribution can be skewed either left or right,depending on λ.

The discrete random variable X is the number of students that show up for Professor Smith's office hours on Monday afternoons.The table below shows the probability distribution for X.What is the expected value E(X)for this distribution?

A discrete binomial distribution is skewed right when π > .50.

The standard deviation of a Poisson random variable is the square root of its mean.

Which is a not a discrete random variable?

Historically,2 percent of the stray dogs in Southfield are unlicensed.On a randomly chosen day,the Southfield city animal control officer picks up seven stray dogs.What is the probability that fewer than two will be unlicensed?

If 5 percent of automobiles in Oakland County have one burned-out headlight,what is the probability that,in a sample of 10 automobiles,none will have a burned-out headlight?

The probability that a ticket holder will miss a flight is .005.If 180 passengers take the flight,what is the approximate Poisson probability that at least 2 will miss the flight?

Which model best describes the number of incorrect fare quotations by a well-trained airline ticket agent between 2 p.m.and 3 p.m.on a particular Thursday.

When you send out a resume,the probability of being called for an interview is .20.What is the probability that you get your first interview within the first five resumes that you send out?

The random variable X is the number of shots it takes before you make the first free throw in basketball.Assuming the probability of success (making a free throw)is constant from trial to trial,what type of distribution does X follow?

A discrete random variable has a countable number of distinct values.

Jankord Jewelers permits the return of their diamond wedding rings,provided the return occurs within two weeks.Typically,10 percent are returned.If eight rings are sold today,what is the probability that fewer than three will be returned?

Overview of Statistics

Data Collection

Describing Data Visually

Descriptive Statistics

Probability

Continuous Probability Distributions

Sampling Distributions and Estimation

One-Sample Hypothesis Tests

Two-Sample Hypothesis Tests

Analysis of Variance

Simple Regression

Multiple Regression

Time-Series Analysis

Chi-Square Tests

Nonparametric Tests

Quality Management

Filters