Mean Frequency Distribution AP Stat

Many professional schools require applicants to take a standardized test. Suppose that 1000 students take such a test. Several weeks after the test, Pete receives his score report: he got a 63, which placed him at the 73rd percentile. This means that

• Pete's score was below the median.

• Pete did worse than about 63% of the test takers.

• Pete did worse than about 73% of the test takers.

• Pete did better than about 63% of the test takers.

• Pete did better than about 73% of the test takers.

• 0

• 1

• 2

• 3

• 5

Rainwater was collected in water collections at 30 different sites near an industrial complex, and the amount of acidity (pH level) was measured. The mean and standard deviation of the values are 4.60 and 1.10, respectively. When the pH meter was re-calibrated back at the laboratory, it was found to be in error. The error can be corrected by adding 0.1 pH units to all of the values and then multiplying the result by 1.2. The mean and standard deviation of the corrected pH measurements are

• 5.64, 1.44

• 5.64, 1.32

• 5.40, 1.44

• 5.40, 1.32

• 5.64, 1.20

• 20%

• 40%

• 50%

• 60%

• 80%

The average yearly snowfall in Chillyville is Normally distributed with a mean of 55 inches. If the snowfall in Chillyville exceeds 60 inches in 15% of the years, what is the standard deviation?

• 4.83 inches

• 5.18 inches

• 6.04 inches

• 8.93 inches

• The standard deviation cannot be computed from the given information.

• The mean of the distribution is E.

• The area between B and F is .50.

• The median of the distribution is C.

• The 3rd quartile of the distribution is D

• The area under the curve between A and G is 1.

The heights of a population of men follow a Normal distribution, and 99.7% have heights between 5'0" and 7'0", what is your estimate of the standard deviation of the heights in this population?

• 1" (inch)

• 3" (inches)

• 4" (inches)

• 6" (inches)

• 12" (inches)

The distribution of the time it takes for different people to solve a certain crossword puzzle is strongly 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 SD 15

• skewed to the right with mean 30 and SD 15

• Normally distributed with mean 0 and SD 1

• skewed to the right with mean 0 and SD 1

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

The EPA requires that the exhaust of each model of motor vehicle be tested for the level of several pollutants. The level of oxides of nitrogen (NOX) in the exhaust of one light truck model was found to vary among individual trucks according to an approximately Normal distribution with mean μ = 1.45 grams per mile driven and standard deviation σ = 0.40 gram per mile. Which of the following best estimates the proportion of light trucks of this model with NOX levels greater than 2 grams per mile?

• 0.0228

• 0.0846

• 0.4256

• 0.9154

• 0.9772

Until the scale was changed in 1995, SAT scores were based on a scale set many years ago. For Math scores, the mean under the old scale was 470 and the standard deviation was 110. In 2016, the mean was 510 and the standard deviation was 103. Gina took the SAT in 1994 and scored 500. Her cousin Colleen took the SAT in 2016 and scored 530. Who did better on the exam, and how can you tell?

• Colleen - she scored 30 points higher than Gina.

• Colleen - her standardized score is higher than Gina's.

• Gina - her standardized score is higher than Colleen's.

• Gina - the standard deviation was larger in 2016.

• The two cousins did equally well - their z-scores are the same.