the 7 marbles be ordered?

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the 7 marbles be ordered?

by sanju09 » Tue Oct 18, 2011 3:31 am
There are 7 marbles-2 black, 3 white, and 2 red, but otherwise not distinguishable. In how many different ways can the 7 marbles be ordered?
(A) 84
(B) 140
(C) 210
(D) 280
(E) 5,040
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by shankar.ashwin » Tue Oct 18, 2011 3:50 am
7!/3!2!2!= 210
C