How many ways can 5 identical black balls and 7 identical : Quant Question Archive [LOCKED]
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How many ways can 5 identical black balls and 7 identical

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How many ways can 5 identical black balls and 7 identical [#permalink]

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27 Dec 2004, 13:12
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

How many ways can 5 identical black balls and 7 identical whie balls be arranged in a row so that no 2 black balls are together?
(A) 56
(B) 64
(C) 65
(D) 316
(E) 560
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27 Dec 2004, 13:34
A : 56
The black balls have to be placed between the 7 white balls.. If we arranage the 7 white balls as _W_W_W_W_W_W_W_. We have 8 spots for balck balls and we have to put 5 of them. therefore required result = 8C5 = 56.
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27 Dec 2004, 13:50
Yep (A)
Nice approach.
27 Dec 2004, 13:50
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