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# There are 3 red chips and 2 blue chips. When arranged in a

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SVP
Joined: 04 May 2006
Posts: 1894
Schools: CBS, Kellogg
There are 3 red chips and 2 blue chips. When arranged in a [#permalink]

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10 May 2008, 18:41
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

There are 3 red chips and 2 blue chips. When arranged in a row, they form a certain color pattern, for example RBRRB. How many color patterns are possible?
A. 10
B. 12
C. 24
D. 60
E. 100
_________________
Director
Joined: 23 Sep 2007
Posts: 783

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10 May 2008, 22:35
1
KUDOS
I got this tip from a guide on this forum:

Permutations Including like Objects. Formula: n! / r¹! r²! .....
where r¹ is the number of one object which are alike and r² is the number of a second object alike, and so on.

There is no choosing.
The order of the objects is important,
You have some objects which are the same.

Example:
You want to arrange 10 books on a shelf but you have 2 copies of one book and 3 copies
of another. The number of ways you can arrange them is 10! / 2! x 3! which equals 3,628,800 ÷ 2 x 6 = 302,400.
SVP
Joined: 04 May 2006
Posts: 1894
Schools: CBS, Kellogg

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12 May 2008, 21:23
gmatnub wrote:
I got this tip from a guide on this forum:

Permutations Including like Objects. Formula: n! / r¹! r²! .....
where r¹ is the number of one object which are alike and r² is the number of a second object alike, and so on.

There is no choosing.
The order of the objects is important,
You have some objects which are the same.

Example:
You want to arrange 10 books on a shelf but you have 2 copies of one book and 3 copies
of another. The number of ways you can arrange them is 10! / 2! x 3! which equals 3,628,800 ÷ 2 x 6 = 302,400.

It is so so sooooo great, I have just kept it in my log!
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CEO
Joined: 17 May 2007
Posts: 2950

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12 May 2008, 21:30
Brilliant stuff gmatnub +1.
Director
Joined: 05 Jan 2008
Posts: 687

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13 May 2008, 01:07
cool I learnt a good one.

+1 gmatnub
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Persistence+Patience+Persistence+Patience=G...O...A...L

Re: color patterns   [#permalink] 13 May 2008, 01:07
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