Statistics Chapter 4, 5, & 6

When the results of experimentation or historical data are used to assign probability values, the method used to assign probabilities is referred to as the _____. a. relative frequency method b. posterior method c. classical method d. subjective method

a

Which of the following is NOT a characteristic of an experiment where the binomial probability distribution is applicable? a. The trials are dependent. b. The probabilities of the outcomes do not change from one trial to another. c. Exactly two outcomes are possible on each trial. d. The experiment has a sequence of n identical trials.

a

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

You roll a fair six-sided die with the hopes of rolling a 5 or a 6. These two events are ___________ because they have no sample points in common. a. mutually exclusive events b. independent events c. complements d. posterior events

a

A magician holds a standard deck of cards and draws one card. The probability of drawing the ace of diamonds is 1/52. What method of assigning probabilities was used? a. subjective method b. classical method c. objective method d. experimental method

b

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

b

A standard normal distribution is a normal distribution with _____. a. a mean of 1 and a standard deviation of 0 b. a mean of 0 and a standard deviation of 1 c. any mean and a standard deviation of 1 d. any mean and any standard deviation

b

A weighted average of the value of a random variable, where the probability function provides weights, is known as _____. a. a probability function b. the expected value c. a random variable d. None of these answers are correct.

b

Check My Work The range of probability is _____, a. any value between -1 to 1 b. 0 to 1, inclusive c. any value between minus infinity to plus infinity d. any value larger than 0

b

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

b

The probability Pete will catch fish when he goes fishing is .8. Pete is going fishing 3 days next week.The expected number of days Pete will catch fish is _____. a. 3 b. 2.4 c. .8 d. .6

b

What type of function defines the probability distribution of ANY continuous random variable? a. Normal distribution function only b. Probability density function c. Both the normal distribution function and the uniform distribution function d. Uniform distribution function only

b

Which of the following statements about a discrete random variable and its probability distribution is true? a. The values of f(x) increase to a maximum point and then decrease. b. Values of f(x) must be greater than or equal to zero. c. Negative values of f(x) are allowed if Σf(x) = 1. d. Values of the random variable can never be negative.

b

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

d

A method of assigning probabilities based upon judgment is referred to as the _____. a. probability method b. relative frequency method c. classical method d. None of these answers are correct.

d

Each customer entering a department store will either buy or not buy some merchandise. An experiment consists of following three customers and determining whether or not they purchase any merchandise. The number of sample points in this experiment is _____. a. 2 b. 4 c. 6 d. 8

d

For a continuous random variable x, the probability density function f(x) represents _____. a. the probability at a given value of x b. the area under the curve at x c. both the probability at a given value of x and the area under the curve at x d. the height of the function at x

d

For any continuous random variable, the probability that the random variable takes on exactly a specific value is _____. a. 1 b. any value between 0 and 1 c. .50 d. 0

d

If the mean of a normal distribution is negative, _____. a. the standard deviation must also be negative b. the variance must also be negative c. a mistake has been made in the computations, because the mean of a normal distribution cannot be negative d. None of these answers are correct.

d

Of five letters (A, B, C, D, and E), two letters are to be selected at random. How many possible selections are there? a. 7 b. 5! c. 20 d. 10

d

On a December day, the probability of snow is .30. The probability of a "cold" day is .50. The probability of snow and a "cold" day is .15. Are snow and "cold" weather independent events? a. only if given that it snowed b. only when they are also mutually exclusive c. no d. yes

d

The highest point of a normal curve occurs at _____. a. approximately three standard deviations to the right of the mean b. two standard deviations to the right of the mean c. one standard deviation to the right of the mean d. the mean

d

The mean of a standard normal probability distribution _____. a. can be any value b. can be any value as long as it is positive c. is always equal to 1 d. None of these answers are correct.

d

The standard deviation of a standard normal distribution _____. a. can be any positive value b. is always equal to 0 c. can be any value d. is always equal to 1

d

Which of the following is NOT a characteristic of the normal probability distribution? a. The random variable assumes a value within plus or minus three standard deviations of its mean 99.72% of the time. b. The total area under the curve is always equal to 1. c. The mean is equal to the median, which is also equal to the mode. d. The graph of the curve is the shape of a rectangle.

d

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

d

The mean, median, and mode have the same value for which of the following probability distributions? a. normal b. uniform c. exponential d. Poisson

a

Twenty percent of the students in a class of 100 are planning to go to graduate school. The standard deviation of this binomial distribution is _____. a. 4 b. 16 c. 20 d. 2

a

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

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

a

For a standard normal distribution, a negative value of z indicates _____. a. the z is to the left of the mean b. the z is to the right of the mean c. a mistake has been made in computations, because z is always positive d. the area corresponding to the z is negative

a

For a uniform probability density function, the height of the function _____. a. is the same for each value of x b. is different for various values of x c. decreases as x increases d. cannot be larger than1

a

In a standard normal distribution, the range of values of z is from _____. a. minus infinity to infinity b. 0 to 1 c. -3.09 to 3.09 d. -1 to 1

a

Larger values of the standard deviation result in a normal curve that is _____. a. wider and flatter b. narrower and more peaked c. shifted to the left d. shifted to the right

a

Suppose we flip a fair coin five times and each time it lands heads up. The probability of landing heads up on the next flip is _____. a. 1/2 b. 1 c. 0 d. None of these answers are correct.

a

The "Top Three" at a racetrack consists of picking the correct order of the first three horses in a race. If there are 10 horses in a particular race, how many "Top Three" outcomes are there? a. 720 b. 1,814,400 c. 10 d. 302,400

a

The expected value of a discrete random variable _____. a. is the average value for the random variable over many repeats of the experiment b. is the most likely or highest probability value for the random variable c. will always be one of the values x can take on, although it may not be the highest probability value for the random variable d. All of these answers are correct.

a

A graphical device used for enumerating sample points in a multiple-step experiment is a _____. a. bar chart b. histogram c. tree diagram d. None of these answers are correct.

c

A numerical description of the outcome of an experiment is called a _____. a. descriptive statistic b. probability function c. random variable d. variance

c

Assume your favorite football team has two games left to finish the season. The outcome of each game can be win, lose, or tie. The number of possible outcomes is _____. a. 4 b. 2 c. 9 d. 6

c

Exhibit 5-8: The student body of a large university consists of 60% female students. A random sample of 8 students is selected. What is the random variable in this experiment? a. the 60% of female students b. the random sample of 8 students c. the number of female students out of 8 d. the student body size

c

For the standard normal probability distribution, the area to the left of the mean is _____. a. any value between 0 and 1 b. -.5 c. 0.5 d. 1

c

The sample space refers to _____. a. any particular experimental outcome b. the sample size minus 1 c. the set of all possible experimental outcomes d. both any particular experimental outcome and the set of all possible experimental outcome

c

The variance is a weighted average of the _____. a. square root of the deviations from the median b. squared deviations from the median c. squared deviations from the mean d. square root of the deviations from the mean

c

When the assumption of equally likely outcomes is used to assign probability values, the method used to assign probabilities is referred to as the _____. a. probability method b. relative frequency method c. classical method d. subjective method

c

Which of the following is NOT a characteristic of the normal probability distribution? a. The mean of the distribution can be negative, zero, or positive. b. The mean, median, and mode are equal. c. The standard deviation must be 1. d. The distribution is symmetrical.

c