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conocieur
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What is the number of different ways to choose a chairman, 11 Nov 2006, 01:44
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What is the number of different ways to choose a chairman, two deputies and two assistants for the class committee out of 7 students up for election?



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What is the number of different ways to choose a chairman, 11 Nov 2006, 02:14
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Is it 670? that sounds like too many, if yes I will post my calc, if not I will feel embarrassed like i do most of the time
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trivikram
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What is the number of different ways to choose a chairman, 11 Nov 2006, 08:36
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Conside two deputies and two assistants as 2 groups than 4 members

So 5!/2!*2! = 30
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What is the number of different ways to choose a chairman, 11 Nov 2006, 21:40
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the answer is 630..... the best strategy (yet again) is to count. no formulas for me please...

so...

starting with the chairman - we have 7 possibilities.
after selecting a chairman, we have to select 2 deputies out of the remaining 6. that's 15 (well, you are allowed to use a formula for that, but you don't have to. for the first deputy you have 6, the second 5 - but since the order of them is not relevant you have to divide by two, as you counted every possibility twice).
we have still to select 2 assistants out of 4 remaining. that's 6.

multiply everything to get the result

7*15*6 = 630

hope it helps.

amit.
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What is the number of different ways to choose a chairman, 12 Nov 2006, 09:13
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Sounds absurd. But I got 630*6 = 3780. Wouldn't it matter whom you pick first.
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What is the number of different ways to choose a chairman, 20 Nov 2006, 18:27
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well done

7! / 2! 2! 1! 2! = 630
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What is the number of different ways to choose a chairman, 21 Nov 2006, 00:08
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What is the number of different ways to choose a chairman, two deputies and two assistants for the class committee out of 7 students up for election?

Number of ways to choose chairman 7
2 deputies should come from rest 6 so 6c2= 6*5/2=15
2 assietnt come from rest od 4 so 4c2 = 4*3/2=6

7*15*6=90*7=630
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What is the number of different ways to choose a chairman, 21 Nov 2006, 00:11
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The answer is 630!
Choosing a chairman 7C1 = 7
Choosing 2 Deputies 6C2 = 15
Choosing 2 Assistants 4C2 = 6
Therefore, totally 7*15*6 = 630...
When we have "AND" in a combination problem, we have to multiply
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What is the number of different ways to choose a chairman, 21 Nov 2006, 02:47
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I get 630 using permutation formula


7P2/2!2!=630

2! and 2! are for the 2 same deputies and 2 same assistants counted double in 7P2



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