Chapter 5: Probability

What is the mean of x, given the exponential probability function f(x) = 1/20e^x/20 for x>=0?

a. 0.05 b. 20 c. 100 d. 2000 b.20

The event containing the outcomes belonging to A or B is the ___ of A and B

a. Venn diagram b. intersection c. union d. complement c. union

The ______ probability distribution can be used to estimate the number of vehicles that go through an intersection during the lunch hour.

a. binomial b. normal c. triangular d. poisson d. poisson

An initial estimate of the probabilities of events is a ______ probability

a. conditional b. empirical c. posterior d. prior d. prior

Bayes' theorem is a method used to compute ________ probabilities

a. conditional b. posterior c. empirical d. prior b. posterior

A variable that can only take on specific numeric values is called a

a. discrete random variable b. continuous random variable c. categorical variable d. categorical variable a. discrete random variable

An experiment consists of determining the speed of automobiles on a highway by the use of radar equipment. The random variable in this experiment is a

a. discrete random variable b. continuous random variable c. complex random variable d. categorical random variable b. continuous random variable

Which statement is true about mutually exclusive events

a. if events A and B cannot occur at the same time, they are called mutually exclusive b. if either event A or event B must occur, they are called mutually exclusive c. P(A) + P(B) = 1 for any events A and B that are mutually exclusive d. none of these are correct A. if events A and B cannot occur at the same time, they are called mutually exclusive

What is the total area under the normal distribution curve?

a. it depends upon the mean and standard deviation b. it must be calculated c. 1 d. 100 c. 1

The triangular distribution is a good model for ____ distributions

a. normal b. normal c. skewed d. uniform c. skewed

Probability is the

a. number of successes divided by the standard deviation of the distribution b. number of successes divided by the number of failures c. numerical measure of the likelihood that an event will occur d. chance that an event will not happen c. numerical measure of the likelihood that an event will occur

All of the following are examples of discrete random variables except

a. number of tickets sold b. marital status c. time d. populations of a city c. time

A _____ describes the range and relative likelihood of all possible values for a random variable.

a. probability distribution for a random variable b. probability mass function of an event c. density function d. probability a. probability distribution for a random variable

A joint probability is the

a. sum of the probabilities of two events b. probability of the intersection of two events c. sum of the probability of the union of two events d. probability of the union of two events b. probability of the intersection of two events

Which of the following statetments is correct?

a. the binomial and normal distributions are both continuous probability distributions b. the binomial distribution is a continuous probability distribution, and the normal distribution is a discrete probability distribution c. the binomial distribution is a discrete probability distribution and the normal distribution is a continuous probability distribution d. the binomial and normal distributions are both discrete probability distributions c. the binomial distribution is a discrete probability distribution and the normal distribution is a continuous probability distribution

The center of a normal curve is

a. the mean of the distribution b. always a positive number c. equal to the standard deviation d. always equal to zero a. the mean of the distribution

which of the following is a discrete random variable?

a. the number of times a student guesses the answers to questions on a certain test b. the amount of gasoline purchased by a customer c. the amount of mercury found in fish caught in the Gulf of Mexico d. the height of water-oak trees a. the number of times a student guesses the answers to questions on a certain test

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

a. the standard deviation must be 1 b. the mean, median, and the mode are equal c. the distribution is symmetrical d. the mean of the distribution can be negative, zero, or positive a. the standard deviation must be 1

Two events are independent if

a. the two events occur at the same time b. the probability of one or both events is greater than 1 c. P(A | B) = P(A) or P(B | A) = P(B) d. none of these are correct c. P(A | B) = P(A) or P(B | A) = P(B)