In a survey of undergraduate library usage, it was found that 76% of seniors, 59% of juniors, 50% of sophomores, and 28% of freshmen use the library frequently. Suppose that 17% of the undergraduates are seniors while the corresponding percentages for juniors, sophomores, and freshmen are 18%, 19%, and 46% respectively.
What percent of the students use the library frequently?
Suppose you see a student use the library everyday. What is the probability that this student is a freshman?