Question 167319: Robert has 4 red flags, 3 blue flags, and 2 white flags. How many 9-flag signals can he run up a flagpole?
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! Robert has 4 red flags, 3 blue flags, and 2 white flags. How many 9-flag signals can he run up a flagpole?
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The problem is the same as "the number of words you could form with 4 R's,
3 B's and 2 W's". If all the letters were different the answer would 9!;
but sice the 4 red flags are indistinguishable the number of distinct words
is reduced by a factor of 4!. The same is true for the 3 blue flags and
also for the 2 white flags.
Hope this helps.
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9!/(4!*3!*2!) = 362880/(24*6*2) = 1260
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Cheers,
Stan H.
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