boarderlee wrote:

10 drinks are available. 6 of them are Pepsi Coke and 4 of them Mountain Dew. You are picking 5 drinks, and least one drink is Moutain Dew. How many ways can you do this?

This is easy:

PC - Pepsi Coke

MD - Mountain Dew

Direct method:

1. Total # of combi of 5 drinks out of 16= 16C5

2. Total # of combi of no MD (all P) = 6C5

3. 1-2 and urdone.

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Indirect method:

1. 4C1*6C4 = Combi of one MD and 4 PC

2. 4C2*6C3 = Combi of two MD and 3 PC

3. 4C3*6C2 = Combi of tree MD and 2 PC

4. 4C4*6C1 = Combi of tree MD and 1 PC

5. 1+2+3+4 = must equal to step 3 in the direct method.

Somebody wants to check?

_________________

Respect,

KL