Ap Stats Ch.2

In 1965, the mean price of a new car was $2,650 and the standard deviation was $1,000. In 2011, the mean was $30,500 and the standard deviation was $9,000. If a Ford Mustang cost $2,300 in 1965 and $28,000 in 2011, in which year was it more expensive relative to other cars?

• 1965, because the standardized score is greater than in 2011.

• 1965, because the standard deviation is smaller.

• 2011, because the standardized score is greater than in 1965.

• 2011, because $28,000 is greater than $2,300.

• We cannot compare the two prices, because we don’t know if the prices for each year are Normally distributed.

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CCSS.HSS.ID.A.4

. The weights of adult male Labrador Retrievers are approximately Normally distributed with a mean of 87 pounds and a standard deviation of 8 pounds. Which of the following statements is true?

• About 95% of adult male Labrador Retrievers weigh between 79 and 95 pounds.

• The median weight of adult male Labrador Retrievers is more than 87 pounds.

• The proportion of adult male Labrador Retrievers that weigh less than 80 pounds is approximately equal to the proportion that weigh more 94 pounds.

• Almost all adult male Labrador retrievers weight more than 79 pounds.

• The standardized weights of 80-pound and 94-pound adult male Labrador Retrievers are roughly equal.

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CCSS.HSS.ID.A.4

Which of the following is true about all Normal distributions?

• There is no area under the curve for z-scores greater than 3.49.

• The area underneath the curve is equal to 1.

• The points at which the curvature changes from “up” to “down” (the points of inflection) are at the first and third quartiles of the distribution.

• About 68% of the values of the variable are more than one standard deviation away from the mean.

• The mean is usually greater than the median

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CCSS.HSS.MD.A.3

CCSS.HSS.MD.A.4

The density curve shown takes the value 0.5 on the interval 0 ≤ x ≤ 2 and takes the value 0 everywhere else. What percent of the observations lie between 0.5 and 1.2?

• 25%

• 35%

• 50%

• 68%

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CCSS.6.SP.B.4

CCSS.HSS.ID.A.1

The 16th percentile in a Normal distribution is 25 and 2.5% of the values in the distribution are greater than 40. Which of the following are the best estimates for the mean and standard deviation of the distribution?

• mean ≈ 32.5; standard deviation ≈ 2.5

• mean ≈ 32.5; standard deviation ≈ 5

• mean ≈ 32.5; standard deviation ≈ 10

• mean ≈ 30; standard deviation ≈ 2.5

• mean ≈ 30; standard deviation ≈ 5

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CCSS.HSS.ID.A.4

A cumulative relative frequency graph for the 48 racers who finished the grueling 50km cross-country ski race at the 2010 Vancouver Olympics is given below.

• 0.17

• 0.40

• 0.45

• 0.50

• 0.55

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CCSS.HSS.ID.A.1

The distribution of the time it takes for different people to solve a certain crossword puzzle is skewed to the right, with a mean of 30 minutes and a standard deviation of 15 minutes. The distribution of z-scores for those times is

• Normally distributed, with mean 30 and standard deviation 15.

• skewed to the right, with mean 30 and standard deviation 15.

• Normally distributed, with mean 0 and standard deviation 1.

• skewed to the right, with mean 0 and standard deviation 1.

• skewed to the right, but the mean and standard deviation cannot be determined without more information.

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CCSS.HSS.IC.B.4

CCSS.HSS.ID.A.4

Which of the following is closest to the 61st percentile of the standard Normal distribution?

• z = –0.7291

• z = –0.28

• z = 0.20

• z = 0.28

• z = 0.7291

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CCSS.HSS.ID.A.4

Here is a Normal probability plot for a set of test scores. Which statement is true for these data?

• The data are Normally distributed.

• The data are approximately Normally distributed.

• The data are skewed to the left.

• The data are skewed to the right.

• There is insufficient information to determine the shape of the distribution.

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CCSS.HSS.ID.A.3

For the density curve shown, which letters correspond to the locations of the mean and median of the distribution?

• Mean = C; Median = B

• Mean = C; Median = C

• Mean = A; Median = B

• Mean = B; Median = B

• Mean = B; Median = A

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CCSS.6.SP.B.5D

CCSS.HSS.ID.A.2