(2) The pass rate is 48? 348× 100%=93.8%

(3) The average score is: 55× 3+65×12+75×15+85× 9+95× 348 = 65 (minutes).

(4) The median falls within 70-80 groups; Only three people failed this course.

So the answers are: (1)48, (2)93.8, (3)65, (4) the median falls within the subgroup of 70-80; Only three people failed this course.