The article "More Students Taking AP Tests" (San Luis Obispo Tribune, January 10, 2003) provided the following information on the percentage of students in grades 11 and 12 taking one or more AP exams and the percentage of exams that earned credit in 1997 and 2002 for seven high schools on the central coast of California.

a. Assuming it is reasonable to regard these seven schools as a random sample of high schools located on the central coast of California, carry out an ap- propriate test to determine if there is convincing evidence that the mean percentages of exams earning college credit at central coast high schools for 1997 and 2002 were different.

b. Do you think it is reasonable to generalize the conclusion of the test in Part (a) to all California high schools? Explain.

c. Would it be reasonable to use the paired t test with the data on percentage of students taking one or more AP classes? Explain.