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September 23rd, 2011, 07:20 AM   #1
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How many words of seven letters

There are letters {a, a, a, b, e, e, c }
How many words of seven letters - different letter queues - can be formed of them?
There has to be for example two times a and so on in the word.

My solution is just n over k:

7

4


( 7, because there are 7 characters and 4 because there are 4 different characters, three are similar )
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September 23rd, 2011, 09:37 AM   #2
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Re: How many words of seven letters

Hello, mike688!

Quote:
There are letters {a, a, a, b, e, e, c }
How many differentwords of seven letters can be formed of them?

My solution is just n over k:[color=beige] .[/color] [color=beige] .[/color] [color=blue] . . . No[/color]

If we had seven different letters, there would be possible permutations.

Since the three 's are identical, our number is too large by a factor of

Since the two 's are identical, our number is too large by a factor of

[color=beige]. . [/color]The number of permutations is:[color=beige] .[/color]

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September 23rd, 2011, 10:56 AM   #3
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Re: How many words of seven letters

Soroban, thank you very much!
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