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Combination Problem

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Combination Problem

by umaa » Wed Jul 29, 2009 2:15 pm
A secretary differentiates files by a variety of color combinations. If she uses 4 different colors, and marks each file with 1, 2, or 3 of the colors, how many different color combinations can she generate?
(A) 4
(B) 12
(C) 14
(D) 15
(E) 24

Explanation pls
Last edited by umaa on Wed Jul 29, 2009 3:49 pm, edited 1 time in total.
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by jjk » Wed Jul 29, 2009 3:39 pm
With 4 different colors, she can create 4 single-color combinations.

With 4 different colors, she can create 4!/[2!(4-2)!] = 6 two-color combinations.

With 4 different colors, she can create 4!/[3!(4-3)!] = 4 different three-color combinations

4 + 6 + 4 = 14

Is the Total GMAT Math explanation not sufficient?
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by umaa » Wed Jul 29, 2009 3:50 pm
Got it!! I misunderstood the question. Thx
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