AP Statistics Chapter 6 Random Variables

Which of the following random variables is discrete?

• The number of shots made in 10 free-throw attempts.

• The weight of a rhinoceros.

• The species of an insect.

• The length of a needle on a saguaro cactus.

• None of the variables above are discrete.

A marketing survey compiled data on the number of personal computers in households. If X = the number of computers in a randomly-selected household, and we omit the rare cases of more than 5 computers, then X has the given distribution. The expected value of X is E(X) =

• 0.40

• 1.00

• 1.45

• 1.66

• 2.50

A marketing survey compiled data on the number of personal computers in households. If X = the number of computers in a randomly-selected household, and we omit the rare cases of more than 5 computers, then X has the given distribution. The standard deviation of X is 1.27. Interpret this value.

• The number of computers in a randomly selected household is within 1.27 of the mean.

• The number of computers in a randomly selected household is exactly 1.27 from the mean.

• The number of computers in a randomly selected household is 1.27, on average.

• The number of computers in a randomly selected household is typically 1.27 from the mean.

• The average number of computers in a randomly selected household is typically 1.27 from the mean.

A marketing survey compiled data on the number of personal computers in households. X = the number of computers in a randomly-selected household. If you were to randomly select households, what is the probability it would take exactly 8 selections to find one with 5 computers?

• Approximately 0

• 0.02

• 0.03

• 0.32

• Approximately 1

Which of the following refers to a rule that assigns a numerical value or characteristic to an outcome of an experiment?

• Expected Value

• Random Variable

• Range Space

• Probability Distribution

• A

• B

• C

• D

• E

It is a variable whose values are determined by chance.

• Random Variable

• Discrete Variable

• Continuous Variable

• Independent Variable

Is this a probability distribution?

• No

• Yes

A random variable is defined by a rule that assigns a _______________ to every outcome in a sample space.

• number

• letter

• Event

• probability

Is this a probability distribution?

• No, the sum of p(x) does not equal 1.

• Yes, all p(x) are between 0 and 1.

• No, all p(x) are not between 0 and 1.

• Yes, the sum p(x) is 1.