Question

a committee of 6 is to be selected from 10 people of whom A and B are two. How many committees can be formed excluding A if B is included?

Answer 1

ecludin A means u left with 9 choices
hence answer is 9C6

Answer 2

incorrect the answer is 140 but i have no idea how they got that

Answer 3

You mean the probability?

that's 10-1 =9

so; 6/9 = 2/3

Answer 4

no i don't mean the probability

Answer 5

oOh, I'm sorry

Answer 6

2 * 1C0 * 1C1 * 8C5 + 1C0*1C0 * 8C6 = 140

First case: A is chosen and B is not.
Second case: B is chosen and A is not
Third case: Neither A nor B is chosen.

Second case is similar to first, that's why I multiplied with 2.

Ask if you don't understand

Answer 7

Explain please.

Answer 8

If A and B may not be together on the committee, it leaves us with three possibilities:

1. A is on, B is not.

1 Choose 0 (Do not choose B) * 1 Choose 1 (Do choose A) * 8 Choose 5 (5 Remaining people on committee)

2. B is on, A is not.

1 Choose 0 (Do not choose A) * 1 Choose 1 (Do choose B) * 8 Choose 5 (5 Remaining people on committee)

3. B and A are NOT on the committee.

1 Choose 0 (Do not choose B) * 1 Choose 0 (Do not choose A) * 8 Choose 6 (6 Remaining people on committee)

Answer 9

So it's basically:

1. 1 guy in 0 spots (Not choose B), 1 guy in 1 spot (Choose A), 8 guys in 5 spots (The remaining).

And so on

Answer 10

Yeah

Answer 11

2 * 1C0 * 1C1 * 8C5 + 1C0*1C0 * 8C6 = 140

i don't understand this?

Answer 12

I explained above