# Business Statistics - Chapter 5: Discrete Probability Distributions Quiz

Which of the following is a characteristic of a binomial experiment? a) The trials are independent. b) The probability of success changes from trial to trial. c) At least two outcomes are possible. d) All of these answers are correct.

a) The trials are independent.

A marketing manager instructs his team to make 80 telephone calls to attempt to sell an insurance policy. The random variable in this experiment is the number of sales made. This random variable is a _____. a) discrete random variable b) continuous random variable c) complex random variable d) None of these answers are correct.

a) discrete random variable

A random variable that can assume only a finite number of values is referred to as a(n) _____. a) discrete random variable b) finite sequence c) infinite sequence d) discrete probability function

a) discrete random variable

A description of how the probabilities are distributed over the values the random variable can assume is called a(n) _____. a) probability distribution b) probability function c) expected value d) random variable

a) probability distribution

In a binomial experiment, the _____. a) probability of success does not change from trial to trial b) probability of success could change from trial to trial, depending on the situation under consideration c) probability of success does change from trial to trial d) All of these answers are correct.

a) probability of success does not change from trial to trial

A production process produces 2% defective parts. A sample of five parts from the production process is selected. What is the probability that the sample contains exactly two defective parts? a) .0004 b) .0038 c) .02 d) .10

b) .0038

In a binomial experiment, the probability of success is .06. What is the probability of two successes in seven trials? a) .0036 b) .0554 c) .28 d) .06

b) .0554

Exhibit 5-2 The probability distribution for the daily sales at Michael's Co. is given below. Daily Sales ($1000s) Probability 40 .1 50 .4 60 .3 70 .2 The probability of having sales of at least $50,000 is _____. a) .5 b) .90 c) .30 d) .10

b) .90

The number of electrical outages in a city varies from day to day. Assume that the number of electrical outages ( x ) in the city has the following probability distribution. x f(x) 0 0.80 1 0.15 2 0.04 3 0.01 The mean and the standard deviation for the number of electrical outages (respectively) are _____. a) 2.6 and 5.77 b) 0.26 and .577 c) 3 and .01 d) 0 and .8

b) 0.26 and .577

The expected value for a binomial probability distribution is _____. a) E(x) = p(1 − p) b) E(x) = np c) E(x) = np(1 − p) d) E(x) = pn(1 − n)

b) E(x) = np

A probability distribution showing the probability of x successes in n trials, where the probability of success does not change from trial to trial, is termed a _____. a) normal probability distribution b) binomial probability distribution c) hypergeometric probability distribution d) uniform probability distribution

b) binomial probability distribution

Highway patrol officers measure the speed of automobiles on a highway using radar equipment. The random variable in this experiment is speed, measured in miles per hour. This random variable is a _____. a) discrete random variable b) complex random variable c) continuous random variable d) None of these answers are correct.

c) continuous random variable

A measure of the average value of a random variable is called a(n) _____. a) standard deviation b) variance c) expected value d) None of these answers are correct.

c) expected value

The standard deviation is the _____. a) variance squared b) square root of the sum of the deviations from the mean c) positive square root of the variance d) same as the expected value

c) positive square root of the variance

Which of the following is NOT a property of a binomial experiment? a) The trials are independent. b) Each outcome can be referred to as a success or a failure. c) The probabilities of the two outcomes can change from one trial to the next. d) The experiment consists of a sequence of n identical trials.

c) The probabilities of the two outcomes can change from one trial to the next.

The variance for the binomial probability distribution is _____. a) Var(x) = np b) Var(x) = p(1 - p) c) Var(x) = np(1 - p) d) Var(x) = n(1 - p)

c) Var(x) = np(1 - p)

If you are conducting an experiment where the probability of a success is .02 and you are interested in the probability of two successes in 15 trials, the correct probability function to use is the _____. a) Poisson probability function b) normal probability density function c) binomial probability function d) standard normal probability density function

c) binomial probability function

Which of the following is(are) required condition(s) for a discrete probability function? a) f(x) < 0 b) Σf(x) = 0 c) f(x) ≥ 1 for all values of x d) None of these answers are correct.

d) None of these answers are correct.

When dealing with the number of occurrences of an event over a specified interval of time or space and when the occurrence or nonoccurrence in any interval is independent of the occurrence or nonoccurrence in any other interval, the appropriate probability distribution is a _____. a) hypergeometric probability distribution b) binomial distribution c) normal distribution d) Poisson distribution

d) Poisson distribution

The key difference between binomial and hypergeometric distributions is that with the hypergeometric distribution the _____. a) probability of success must be less than .5 b) probability of success changes from trial to trial c) random variable is continuous d) trials are independent of each other

b) probability of success changes from trial to trial