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Sequence

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Sequence

by mgmt_gmat » Fri Feb 12, 2010 1:02 am
How many different 6-letter sequences are there that consist of 1 A, 2 B's, and 3 C's ?
A. 6
B. 60
C. 120
D. 360
E. 720

Please explain.
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by papgust » Fri Feb 12, 2010 1:59 am
Hi mgmt_gmat,

I've noticed several times that you are not using "Search" before you post a question. Please use the "Search" button. Here it is,
https://www.beatthegmat.com/tough-sequences-t25116.html
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by komal » Tue Feb 16, 2010 7:28 pm
mgmt_gmat wrote:How many different 6-letter sequences are there that consist of 1 A, 2 B's, and 3 C's ?
A. 6
B. 60
C. 120
D. 360
E. 720

Please explain.
Consider each letter seperately,
- There is 1 A, we have 6 places to put this in - 6C1
- There are 2 B's, we have 5 places for this - 5C2
- There are 3 C's, we have 3 places - 3C3
Total possible = 6C1*5C2*3C3 = 6*10*1 = 60 ways
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by thephoenix » Tue Feb 16, 2010 8:46 pm
its 6!/(3!*2!)=60
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