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Chapter 03 - Discrete RV's and Probability Distributions

W E B Q U I Z : Devore, Probability and Statistics for Engineering & the Sciences Chapter 3

QUIZ

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What type of random variable has only two possible values, 0 and 1?

a. a continuous random variable

b. a probability random variable

c. all random variables

d. a Bernoulli random variable

Suppose the gender is recorded for babies born at a local hospital in a twelve-hour period. What type of random variable is being recorded?

a. Continuous

b. Multivariate

c. Probability

d. Discrete

Suppose a quiz is given in a statistics class with 5 multiple-choice questions and 3 true or false questions. What are the possible values for the number of students who answered all of the true and false questions correctly if there are 15 students in the class?

a. 0, 1, 2, 3, 4, 5

b. 0, 1, 2, 3

c. 0, 1, 2, 3, 4, 5, 6, 7, 8

d. All whole numbers from 0 to 15 including 0 and 15.

Which of the following is not an example of a Bernoulli random variable?

a. X = whether or not the next person in the checkout at a grocer spends more than $50

b. C = the gender of a person having surgery for coronary artery disease

c. W = whether or not a light bulb works

d. U = the number of people who pre-register for an engineering class

Which of the following is not true for a probability mass function?

Using the probability distribution given below, what is the value for ?

Suppose X is defined as the number of rolls needed to roll a six on a fair die. What is the probability of having to roll the fair die 3 times before rolling a 6?

a. 1/6

b. 0.28

c. 0.005

d. 0.50

Fill in the blank. A family of probability distributions is the collection of all probability distributions for different values of a ________.

a. statistic

b. mean

c. random variable

d. parameter

What is the value for F(3.5) using the pmf given below?

since

is not a possible value in this pmf.

10.

Suppose M = the number of months that an employee injured on the job collects workers compensation from a randomly selected employee at a large manufacturing company. Given the following values of the cumulative distribution function, what is the ?

CDF:

11.

Using the example where M = the number of months that an employee injured on the job collects workers compensation from a randomly selected employee at a large manufacturing company, what is the given the values of the cumulative distribution function below?

CDF:

12.

Suppose an American household is chosen at random and the random variable x is the number of televisions in the household. The probability distribution of x is as follows:

a. 0.25

b. 2.5

c. 1.95

d. 2

13.

What is the mean value, E(x), for a Bernoulli random variable with a probability of equal to 0.38?

b. The value for E(x) cannot be determined from the information given.

14.

Suppose the , what is the expected value of ?

a. 5.25

b. 16.75

c. It depends on the value of X.

d. 4

15.

Suppose Z has a pmf p(z) and an expected value of . Which of the following is not a valid formula for computing the variance of Z?

16.

Suppose the variance of the number of students (X) who passed the first exam in a college math class is 1.25. What is the variance of the number of students who passed the class for the semester if the function relating those passing the first test to those passing the class is ?