AP Stats Final Review 2020

A data set of test scores is being transformed by applying the following rule to each of the raw scores.

Transformed score = 3.5(raw score) + 6.2

Which of the following is NOT true?

• The mean transformed score equals 3.5(the mean raw score) + 6.2.

• The median transformed score equals 3.5(the median raw score) + 6.2.

• The range of the transformed scores equals 3.5(the range of the raw scores) + 6.2

• The standard deviation of the transformed scores equals 3.5(the standard deviation of the raw scores).

• The IQR of the transformed scores equals 3.5(the IQR of the raw scores).

A sleep time of 15.9 hours per day for a newborn baby is at the 10th percentile of the distribution of sleep times for all newborn babies. Assuming the distribution is normal with standard deviation 0.5 hour, approximately what is the mean sleep time, in hours per day, for newborn babies?

• 15.1

• 15.3

• 16.3

• 16.5

• 16.7

The bar chart displays the relative frequency of responses of students, by grade level, when asked, “Do you volunteer in a community-service activity?” Which of the following statements is not supported by the bar chart?

• More than 60% of both tenth-grade and eleventh-grade students responded yes

• Twelfth-grade students had the least percentage of students respond yes.

• Less than 40% of tenth-grade students responded no.

• The number of tenth-grade students who responded yes was greater than the number of ninthgrade students who responded yes.

• The percentage of eleventh-grade students who responded no was less than the percentage of ninth-grade students who responded no.

A researcher collected data on the age, in years, and the growth of sea turtles. The graph above is a residual plot of the regression of growth versus age. Does the residual plot support the appropriateness of a linear model?

• Yes, because there is a clear pattern displayed in the residual plot.

• Yes, because about half the residuals are positive and the other half are negative.

• Yes, because as age increases, the residuals increase.

• No, because the points appear to be randomly distributed.

• No, because the graph displays a U-shaped pattern.

An agriculturalist working with Australian pine trees wanted to investigate the relationship between the age and the height of the Australian pine. A random sample of Australian pine trees was selected, and the age, in years, and the height, in meters, was recorded for each tree in the sample. Based on the recorded data, the agriculturalist created the following regression equation to predict the height, in meters, of the Australian pine based on the age, in years, of the tree. predicted height = 0.29 + 0.48(age) Which of the following is the best interpretation of the slope of the regression line?

• The height increases, on average, by 1 meter each 0.48 year

• The height increases, on average, by 0.48 meter each year.

• The height increases, on average, by 0.29 meter each year.

• The height increases, on average, by 0.29 meter each 0.48 year

• The difference between the actual height and the predicted height is, on average, 0.48 meter for each year.

A program exists to encourage more middle school students to major in math and science when they go to college. The organizers of the program want to estimate the proportion of students who, after completing the program, go on to major in math or science in college. The organizers will select a sample of students from a list of all students who completed the program. Which of the following sampling methods describes a stratified random sample?

• Select all female students on the list.

• Randomly select 50 students on the list.

• Randomize the names on the list and then select every tenth student on the randomized list.

• Randomly select 25 names from the female students on the list and randomly select 25 names from the male students on the list.

• Randomly select 50 students on the list who are attending college

A researcher conducting a telephone survey is concerned about possible sources of bias. Of the following, which is the best example of nonresponse bias?

• The wording of the questions in the survey leads people to respond in a certain way.

• The behavior of the interviewer leads people to respond in a certain way

• People might be uncomfortable with the survey questions and, as a result, might not always respond to those questions truthfully.

• Many of the people selected to participate in the survey who do not respond might have opinions different from those who do respond.

• People without telephones are overlooked in the sampling procedure used to determine who is surveyed.

A dog food company wishes to test a new high-protein formula for puppy food to determine whether it promotes faster weight gain than the existing formula for that puppy food. Puppies participating in an experiment will be weighed at weaning (when they begin to eat puppy food) and will be weighed at one-month intervals for one year. In designing this experiment, the investigators wish to reduce the variability due to natural differences in puppy growth rates. Which of the following strategies is most appropriate for accomplishing this?

• Block on dog breed and randomly assign puppies to existing and new formula groups within each breed.

• Block on geographic location and randomly assign puppies to existing and new formula groups within each geographic area.

• Stratify on dog breed and randomly sample puppies within each breed. Then assign puppies by breed to either the existing or the new formula.

• Stratify on geographic location of the puppies and randomly sample puppies within each geographic area. Then assign puppies by geographic area to either the existing or the new formula.

• Stratify on gender and randomly sample puppies within gender groups. Then assign puppies by gender to either the existing or the new formula.

For flights from a particular airport in January, there is a 30 percent chance of a flight being delayed because of icy weather. If a flight is delayed because of icy weather, there is a 10 percent chance the flight will also be delayed because of a mechanical problem. If a flight is not delayed because of icy weather, there is a 5 percent chance that it will be delayed because of a mechanical problem. If one flight is selected at random from the airport in January, what is the probability that the flight selected will have at least one of the two types of delays?

• 0.065

• 0.335

• 0.350

• 0.450

• 0.665

• 0

• 1.00

• 1.79

• 3.50

• 28