A school dance committee is made up of 3 freshmen, 6 sophomores, 3 juniors, and 2 seniors.
(a) How many ways are there to sit the committee in a row at a meeting if the students must sit together by grade?
(b) How many ways are there to sit the committee in a row at a meeting if the freshman, sophomores, and juniors must sit by grade, but the seniors can sit wherever they want?