AP Stats Random Variables Practice

A small store keeps track of the number X of customers that make a purchase during the first hour that the store is open each day.  Based on the records, X has the following probability distribution.
The mean number of customers that make a purchase during the first hour that the store is open is:
   

• 2.0

• 2.5

• 2.9

• 3

A small store keeps track of the number X of customers that make a purchase during the first hour that the store is open each day.  Based on the records, X has the following probability distribution.
The standard deviation of the number of customers that make a purchase during the first hour that the store is open is

• 0.2

• 1.4

• 2.0

• 3.0

A company states that 2% of its computers are returned for defects.  We take a sample of 100 computers to find the probability of 10 being defective.  Is this a binomial distribution?

• No because there is not a fixed number of trials.

• No because their are more than 2 outcomes.

• Yes since there are a fixed number of independent trials, outcomes in 2 categories, and the probability of defect is constant.

• No since computers would not be independent.

Suppose you pay $1.00 to roll a fair die with the understanding you will get $3.00 back rolling a 4 or a 2, and nothing otherwise.  What is the expected amount you win?

• $0.00

• -$1.00

• $1.00

• $3.00

• A

• B

• C

• D

• F

It is a variable whose values are determined by chance.

• Random Variable

• Discrete Variable

• Continuous Variable

• Independent Variable

• A

• B

• C

• D

• E

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 teacher gives a 10-question multiple-choice quiz. Each question has four possible answers, and a student randomly guesses the answers to all 10 questions. What is the probability that the student gets at least 8 questions correct?

• A. 0.0034

• B. 0.0193

• C. 0.0439

• D. 0.1094

• A

• B

• C

• D

• E