A survey of randomly selected college students found that 58 of the 90 freshmen and 61 of the 125 sophomores surveyed had purchased used textbooks in...

A survey of randomly selected college students found that 58 of the 90 freshmen and 61 of the 125 sophomores surveyed had purchased used textbooks in the past year. Construct a 99% confidence interval for the difference in the proportions of college freshmen and sophomores who purchased used textbooks.