(2) Let the total number of students in 2008 be 1.
The average loan amount of junior middle school students is 1642÷80%=2052.5.
The amount of books borrowed per senior high school student is 252÷ 12%=2 100.
Then high school students borrow a lot of books per capita;
(3) Let the total number of students in the whole school be 1 in 2007, and the average book borrowing amount of junior middle school students be 1.520÷75% = 2026.7.
At the beginning of 2008, middle school students borrowed a lot of books per capita.