23. We are interested in a 95% confidence interval for the population mean commuting distance. The margin of error associated with the confidence interval is

a. 2.68 miles.

b. 4.64 miles.

c. 5.62 miles.

d. 6.84 miles.

24. A 90% confidence interval for the population mean commuting distance based on these data is

a. 64 2.68 miles.

b. 64 4.64 miles.

c. 64 5.62 miles.

d. 64 6.84 miles.

25. Which of the following is an example of a matched pairs design?

a. A teacher compares the pre-test and post-test scores of students.

b. A teacher compares the scores of students using a computerbased method of instruction, with the scores of other students using a traditional method of instruction.

c. A teacher compares the scores of students in her class on a standardized test with the national average score. 7

d. A teacher calculates the average of scores of students on a pair of tests and wishes to see if this average is larger than 80%.