AP Stats Chapter 8 Review

A sociologist was investigating the ages of grandparents of high school students. From a random sample of 10 high school students, the sociologist collected data on the current ages, in years, of the students’ maternal grandparents. The data are shown in the table below. The data will be used to construct a 95% confidence interval for the population mean difference in age (age of grandmother minus age of grandfather) of the maternal grandparents of high school students. Which of the following is the standard error of the sample mean differences in ages of grandmothers and grandfathers (i.e. sx=)?

• 5.81

• 1.84

• 4.16

• 3.60

• 1.71

A guidance counselor wishes to determine the mean number of changes in academic major by college students to within ±0.1 changes at a 90 percent confidence level. What sample size should be chosen if it is known that the standard deviation is 0.45 changes?

• 8

• 13

• 55

• 78

Which of the following are true statements?

I. Sample parameters are used to make inferences about population statistics.

II. Statistics from smaller samples have more variability.

III. Parameters are fixed, while statistics vary depending on which sample is chosen.

• III only

• I and II

• I and III

• II and III

• None are correct

A coffee house owner knows that customers pour different amounts of coffee into their cups. She samples cups from 10 customers she believes to be representative of the customers and weighs the cups, finding a mean of 12.5 ounces and a standard deviation of 0.5 ounces. Assuming these cups of coffee can be considered a random sample of all cups of coffee which of the following formulas gives a 95% confidence interval for the mean weight of all cups of coffee?

To determine the average speed of cars on a particular highway, police officers recorded the speeds of 23 cars. The 1-mean t-interval they calculated was (29.478 mph, 32.522 mph). What was the margin of error?

• 1.522

• 3.044

• 1.960

• Cannot be determined

A newspaper article would like to collect a sample of people to ask their opinions on a new bill that is being voted on. They would like to report results with 98% confidence that the true proportion is estimated to within 3%. What is the minimum number of people should be in their sample?

• 39

• 1068

• 1503

• 3006

• Cannot be determined

Gambling is an issue of great concern to those involved in college athletics. Because of this concern, the National Collegiate Athletic Association surveyed randomly selected student-athletes on their gambling-related behaviors. Of the 5594 Division I male athletes in the survey, 3547 reported participation in some gambling behavior. What is the parameter of interest?

• the proportion of all Division I male athletes who have participated in gambling behavior.

• all student-athletes

• the 3547 male athletes

• the proportion of the 5594 surveyed male athletes who have participated in gambling behavior.

• gambling behavior

Which of the following can be used to justify normality to create a confidence interval for quantitative data?

• I only

• I and III only

• II, III, and IV only

• I, II, III, and IV

Which of the following is NOT a condition for a 1-proportion z-interval?

• The data is randomly selected.

• The data is normally distributed.

• The data values are independent from one another.

• The sample size is large enough.

True or false:

T-models in general are skinner in the middle of the model than Normal

Models.

• True

• False