AP Statistics Exam Review

A small town employs 34 salaried, nonunion employees. Each employee receives an annual salary increase of between $500 and $2000 based on a performance review by the mayor’s staff. Some employees are members of the mayor’s political party, and the rest are not.

Students at the local high school form two lists, A and B, one for the raises granted to employees who are in the mayor’s party, and the other for raises granted to employees who are not. They want to display a graph (or graphs) of the salary increases in the student newspaper that readers can use to judge whether the two groups of employees have been treated in a reasonably equitable manner.

Which of the following displays is least likely to be useful to readers for this purpose?

• Back-to-back stemplots of A and B

• Scatterplot of B versus A

• Parallel boxplots of A and B

• Histograms of A and B that are drawn to the same scale.

• Dotplots of A and B that are drawn to the same scale.

A consulting statistician reported the results from a learning experiment to a psychologist. The report stated that on one particular phase of the experiment a statistical test result yielded a p-value of 0.24. Based on this p-value, which of the following conclusions should the psychologist make?

• The test was statistically significant because a p-value of 0.24 is greater than a significance level of 0.05.

• The test was statistically significant because p = 1 − 0.24 = 0.76 and this is greater than a significance level of 0.05

• The test was not statistically significant because 2 times 0.24 = 0.48 and that is less than 0.5

• The test was not statistically significant because, if the null hypothesis is true, one could expect to get a test statistic at least as extreme as that observed 24% of the time.

• The test was not statistically significant because, if the null hypothesis is true, one could expect to get a test statistic at least as extreme as that observed 76% of the time.

The correlation between two scores X and Y is equal to 0.8. If both of the X and the Y scores are converted to z-scores, then the correlation between the z-scores for X and the z-scores for Y would be

• ‒ 0.8

• ‒ 0.2

• 0.0

• 0.2

• 0.8

Tags

CCSS.HSS.ID.C.8

• The slope decreased and the r² increased.
• The slope increased and the r² decreased.
• The slope decreased but r² remained the same.
• Both slope and r² remained the same.

Tags

CCSS.HSS.ID.C.8

CCSS.HSS.ID.A.3

CCSS.HSS.ID.B.6

CCSS.HSS.ID.C.7

The Physicians' Health Study, a large medical experiment involving 22,000 male physicians, attempted to determine whether aspirin could help prevent heart attacks. In this study, one group of about 11,000 physicians took an aspirin every other day, while a control group took a placebo. After several years, it was determined that the physicians in the group that took aspirin had significantly fewer heart attacks than the physicians in the control group. Which of the following statements explains why it would not be appropriate to say that everyone should take an aspirin every other day?

I. The study included only physicians, and different results may occur in individuals in other occu­pations.

II. The study included only males and there may be different results for females.

III. Although taking aspirin may be helpful in preventing heart attacks, it may be harmful to some other aspects of health.

• I only

• II only

• III only

• II and III only

• I, II, and III

Tags

CCSS.7.SP.A.1

CCSS.HSS.IC.A.1

A randomized block design will be used in an experiment to compare two lotions that protect people from getting sunburned. Which of the following should guide the formation of the blocks?

• Participants in the same block should receive the same lotion.

• Participants should be randomly assigned to the blocks.

• Participants should be kept blind as to which block they are in.

• Participants within each block should be as similar as possible with respect to how easily they get sunburned.

• Participants within each block should be as different as possible with respect to how easily they get sunburned.

Tags

CCSS.HSS.IC.B.3

Monthly rent was determined for each apartment in a random sample of 100 apartments. The sample mean was

$820 and the sample standard deviation was $25. An approximate 95 percent confidence interval for the true

mean monthly rent for the population of apartments from which this sample was selected is ($815, $825). Which

of the following statements is a correct interpretation of the 95 percent confidence level?

• In this population, about 95 percent of all rental prices are between $815 and $825.

• In this sample, about 95 percent of the 100 rental prices are between $815 and $825.

• In repeated sampling, the method produces intervals that include the population mean monthly rent approximately 95 percent of the time.

• In repeated sampling, the method produces intervals that include the sample mean monthly rent approximately 95 percent of the time.

• There is a probability of 0.95 that the true mean monthly rent is between $815 and $825.

Tags

CCSS.HSS.IC.B.4

A certain county has 1,000 farms. Corn is grown on 100 of these farms but on none of the others. In order to estimate the total farm acreage of corn for the county, two plans are proposed.

Plan I:

(a) Sample 20 farms at random.

(b) Estimate the mean acreage of corn per farm in a confidence interval.

(c) Multiply both ends of the interval by 1,000 to get an interval estimate of the total.

Plan II:

(a) Identify the 100 corn-growing farms.

(b) Sample 20 com-growing farms at random.

(c) Estimate the mean acreage of corn for corn-growing farms in a confidence interval.

(d) Multiply both ends of the interval by 100 to get an interval estimate of the total.

On the basis of the information given, which of the following is the better method for estimating the total farm acreage of corn for the county?

• Choose plan I over plan II

• Choose plan II over plan I

• Choose either plan, since both are good and will produce equivalent results.

• Choose neither plan, since neither estimates the total farm acreage of corn.

• The plans cannot be evaluated from the information given.

Tags

CCSS.7.SP.A.2

9. To check the effect of cold temperature on the elasticity of two brands of rubber bands, one box of Brand A and one box of Brand B rubber bands are tested. Ten bands from the Brand A box are placed in a freezer for two hours and ten bands from the Brand B box are kept at room temperature. The amount of stretch before breakage is measured on each rubber band, and the mean for the cold bands is compared to the mean for the others. Is this a good experimental design?

• No, because the means are not proper statistics for comparison.

• No, because more than two brands should be used.

• No, because more temperatures should be used.

• No, because temperature is confounded with brand.

• Yes.

Tags

CCSS.HSS.IC.B.3

Based on previous research, the standard deviation of the distribution of the age at which children begin to walk

is estimated to be 1.5 months. A random sample of children will be selected, and the age at which each child

begins to walk will be recorded. A 99 percent confidence interval for the average age at which children begin to

walk will be constructed using the data obtained from the sample of children. Of the following, which is the

smallest sample size that will result in a margin of error of 0.1 month or less for the confidence interval?

• 400

• 900

• 1300

• 1600

• 2100