Question

From a group of 5 freshmen, 3 sophomores, 4 juniors, and 6 seniors, how many 5-person committees are possible if there must be exactly 3 seniors?

Answer 1

Well, assuming the question means that there are only 3 seniors in total in all committees, just add all the values, except the senior value (add 3 instead of 6), and divide by 5.
5+3+4+3=15
15/5=3
Only 3 possible total committees. That's only if what I said above is true; the question is worded strangely.