Chapter 6 AP Stat Free Response

The probability that an American household will have at most 3 cars is...

• 0.93

• 0.20

• 0.13

• 0.07

The probability that an American household will have at least 2 cars is...

• 0.55

• 0.35

• 0.45

• 0.93

What's the expected number of cars in a randomly selected American household?

• 1.00

• 1.75

• 1.84

• 2.00

How would you interpret the expected value in number 3?

• The maximum number of cars for the household is Exp(C).

• The average number of cars for the household is Exp(C).

• If we randomly select many households, the average number of cars per household will be approximately by Exp(C).

• If we randomly select many households, the average number of cars per household will vary approximately by Exp(C).

The standard deviation of X is o_x = 1.08. If many households were selected at random, which of the following would be the best interpretation of the value 1.08?

• The mean number of cars would be about 1.08.

• If we randomly selected many households, the number of cars would typically vary be about 1.08 cars from the mean.

• The number of cars would be at most 1.08 from the mean.

• The number of cars would be within 1.08 from the mean about 68% of the time.

• The mean number of cars would be about 1.08 from the expected value.

A deck of cards contains 52 cards , of which 4 are aces. You are offered the following wager: Draw one card at random from the deck. You win $10 if the card drawn is an ace. Otherwise, you lose $1. If you make this wager very many times, what will be the mean amount you win?

• About -$1, because you will lose most of the time.

• About $9, because you win $10 but lose only $1.

• About -$0.15; that is, on average you lose about 15 cents.

• About $0.77; that is, on average you win about 77 cents.

• About $0, because the random draw gives you a fair bet.

The number of calories in a 1-ounce serving of a certain breakfast cereal is a random variable with mean 110 and standard deviation 10. The number of calories in a cup of whole milk is a random variable with mean 140 and standard deviation 12. For breakfast, you eat 1 ounce of the cereal and 1/2 cup of whole milk. Let T be the random variable that represents the total number of calories in this breakfast. The mean of T is...

• 110

• 140

• 180

• 195

The number of calories in a 1-ounce serving of a certain breakfast cereal is a random variable with mean 110 and standard deviation 10. The number of calories in a cup of whole milk is a random variable with mean 140 and standard deviation 12. For breakfast, you eat 1 ounce of the cereal and 1/2 cup of whole milk. Let T be the random variable that represents the total number of calories in this breakfast. The standard deviation of T is...

• 22

• 16

• 15.62

• 11.66

It turns out that 25 seniors at Fashionable High School took both the AP Statistics exam and the AP Spanish Language exam. The mean score on the Statistics exam for the 25 seniors was 2.4 with standard deviation of 0.6, and the mean score on the Spanish Language exam was 2.65 with a standard deviation of 0.55. We want to combine the scores into a single score. What are the correct mean and standard deviation of the combined scores?

• 5.05; 1.15

• 5.05; 1.07

• 5.05; 0.66

• 5.05; 0.81

• 5.05; You cannot determine the standard deviation from this information.

Which of the following variables are continuous?

• Let X be the length of a randomly selected telephone call in minutes.

• Let X be the number of students present.

• Let X be the number of red marbles in the jar.

• Let X be the number of tails when flipping two coins.

• Let X be the student's grade level.