In a large northwestern university, an SRS of 100 entering freshmen in 1988 found that 20 finished in the bottom third of their high school class. Admission standards at the university were tightened in 1990. In 1992 an SRS of 100 entering freshmen found that 10 finished in the bottom third of their high school class. Letting p1 and p2 be the proportion of all entering freshmen in 1988 and 1992, who graduated in the bottom third of their high school class?
Using the above data, construct a 99% confidence interval for p1 and p2.