Counting Problem frmo Combination Lessons : Quant Question Archive [LOCKED]
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# Counting Problem frmo Combination Lessons

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Counting Problem frmo Combination Lessons [#permalink]

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29 Jul 2004, 09:05
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

Hi,

This question is from the combinations lesson posted here.

How many different signals can be transmitted by hoisting 3 red, 4 yellow and 2 blue flags on a pole, assuming that in transmitting a signal, all nine flags are to be used ?

Any idea how it should be solved ?
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29 Jul 2004, 18:11
The Answer is 9!/(3!*2!*4!).

We divide 9! by 3!, 4! and 2! because there are identical 3 red, 4 yellow and 2 blue flags. Best way to remember solving such problem is that, if there are n things and r out of them are identical, then it is n!/r!.

Last edited by venksune on 29 Jul 2004, 19:45, edited 1 time in total.
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29 Jul 2004, 19:01
Hi Venksune !!

That r!/n! was really new to me. Learnt something new today again !
29 Jul 2004, 19:01
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# Counting Problem frmo Combination Lessons

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