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yvonne12
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Topic: gmat prep
PostWed Mar 07, 2007 3:27 pm
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2 members of a club are to be selected to represent the club at a national meeting. if there are 190 different possible selections of 2 members, how many members does the club have?

please explain
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Argen
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PostWed Mar 07, 2007 4:15 pm
nC2=n!/((n-2)!2!)=190
n(n-1)=380
n=20
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yvonne12
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PostWed Mar 07, 2007 9:23 pm
thank you
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Cybermusings
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PostTue Mar 27, 2007 1:58 am
190 selections of "n" members taken 2 at a time...

Which means nC2 = 190

n! /(n-2)! * 2! = 190

n*n-1*n-2!/n-2!*2=190

n*n-1=380
Therefore n=20
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