## Permutations Combinations IB math HL

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### Permutations Combinations IB math HL

Permutations Combinations - IB Mathematics HL - IB maths Higher Level

How can we find the number of possible choices for choosing a sub-committee of five persons consisting of the chairperson, secretary and three ordinary members from a committee of 40 people?

Thanks
Jack

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Joined: Mon Jan 28, 2013 8:08 pm

### Re: Permutations Combinations IB math HL

Permutations, Combinations - IB Maths HL

The chairperson can be chosen by $^{40}\mathrm{C}_1$ ways

The secretary can be chosen by $^{39}\mathrm{C}_1$ ways

And the three ordinary members can be chosen by $^{38}\mathrm{C}_3$ ways

So, the members of this sub-committee can be chosen by

$^{40}\mathrm{C}_1 \cdot ^{39}\mathrm{C}_1 \cdot ^{38}\mathrm{C}_3 =$

$=40 \cdot 39 \cdot 8436 =13,160,160$ ways.
elizabeth

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Joined: Mon Jan 28, 2013 8:09 pm

### Re: Permutations Combinations IB math HL

Thank you!!
Jack

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Joined: Mon Jan 28, 2013 8:08 pm

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