Question

1.Issam has 11 different CDs of which 6 are pop music , 3 are jazz and 2 are classical. Issam makes a selection of 2 pop music CDs, 2 jazz CDs and 1 classical CD. How many different selections can be made.Here the answer is 90 finalized by multiplying all.

2.A committee of 5 people is to be chosen from 6 men and 4 women. In how many ways can this be done If there must be more men than women on the committee.Here we need to add all outcomes.
WHY THESE QUESTIONS NEED ADDITION AND MULTIPLICATION?

Answer 1

There are 6C2 ways to pick the pop CDs, 3C2 ways to pick jazz,and 2C1 ways to pick classical. You multiply because the separate classifications are independent. For each way to pick the jazz, there are 3C2 ways to pick the pop, etc.

For the committee, there are several ways to pick people.
5 men 0 women
4 men 1 woman
3 men 2 women
So figure the combinations for each make-up, and add them together. You need to add, because the various populations are mutually exclusive.

Answer 2

Can you make me clear how various population are mutually exclusive?

Answer 3

come on. You cannot simultaneously have 5 men and only 4 men.
Think about it.