1.In a true false test there are 12 questions. If a student decides to check six of each at random, in how many ways can she do it.

(I was thinking the answer would be 12 choose 6 or 12!/6!) Can anybody explain there reasoning in arriving to their answer.

2.in how many ways can a committee of 3 be chosen from 20 people? In how many ways can a president, a secretary and a treasurer be chosen?

(For the second part of this question i was thinking it was 20!, 19!, 18!)

Thanks again for any replies.