Thank you in advance. please if possible, explain for me, so i can solve other problems by myself (Rofl)

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- October 20th 2008, 03:56 AMNarek1 combination problem
Thank you in advance. please if possible, explain for me, so i can solve other problems by myself (Rofl)

- October 20th 2008, 04:05 AMddt
- October 20th 2008, 05:47 AMNarek
- October 20th 2008, 06:42 AMddt
OK, but it wasn't clear what part of the problem you didn't understand.

So, taking the first of your questions:

"How many bit strings of length 10 have exactly three 0s?"

is equivalent to asking: in how many ways can I make a set of 3 positions out of 10? (the positions being the positions in the bit string where the 0s occur - the other 7 positions then have 1s).

Can you answer that question?

Hint: Combinations; Binomium of Newton. - October 20th 2008, 06:51 AMNarekI ANSWERED IT!
i tried to answer them. is these true?

a) C(10,2)

b) C(10,5)

c) C(10,7) + C(10,8) + C(10,9) + C(10,10)

d) C(10,3) + C(10,4) + C(10,5) + C(10,6) + C(10,7) + C(10,8) + C(10,9) + C(10,10)

Thank you (Rofl) - October 20th 2008, 07:20 AMddt