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windsylph
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How many bit strings of length 10 contain exactly 5 bits equal to 1? Is it 2^10  2^5?
 2 years ago
 2 years ago
windsylph Group Title
How many bit strings of length 10 contain exactly 5 bits equal to 1? Is it 2^10  2^5?
 2 years ago
 2 years ago

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TuringTest Group TitleBest ResponseYou've already chosen the best response.0
I have no idea what this means :(
 2 years ago

TuringTest Group TitleBest ResponseYou've already chosen the best response.0
you have some number of bits of string length 10 and you want to know "how many contain 5 bits equal to 1" ?? what do you mean, 5 pieces of string equal to one what?
 2 years ago

windsylph Group TitleBest ResponseYou've already chosen the best response.0
Sorry, this was gotten straight from the problem statement. I'll rephrase this a little bit. How many 10bit strings are there that have exactly five 1's in them?
 2 years ago

TuringTest Group TitleBest ResponseYou've already chosen the best response.0
@asnaseer can you lend a hand?
 2 years ago

windsylph Group TitleBest ResponseYou've already chosen the best response.0
the 1's can be in any nth bit. doesn't have to be next to each other :D
 2 years ago

TuringTest Group TitleBest ResponseYou've already chosen the best response.0
my impulse is to agree with you, 2^102^5, but combinatorics is not my strong suit
 2 years ago

windsylph Group TitleBest ResponseYou've already chosen the best response.0
Thank you. And it's alright. :D
 2 years ago

phi Group TitleBest ResponseYou've already chosen the best response.1
isn't it just 10 choose 5 ? \[\left(\begin{matrix}10 \\ 5\end{matrix}\right)=\frac{10!}{5! 5!}\]
 2 years ago

windsylph Group TitleBest ResponseYou've already chosen the best response.0
Hm. I'm a little bit fuzzy with combinations right now. 10 choose 5 because..?
 2 years ago

phi Group TitleBest ResponseYou've already chosen the best response.1
does this explain it? http://answers.yahoo.com/question/index?qid=20091122040726AAi6YU0
 2 years ago

phi Group TitleBest ResponseYou've already chosen the best response.1
Or http://answers.yahoo.com/question/index;_ylt=AhmQsH93Xi0bJtqIFdcUKLMCxgt.;_ylv=3?qid=20080504195059AAir3Ep the intuition is that you have 10 spaces all filled with 0's. You choose 5 of the zeros to be replaced with a 1. How many ways can we choose 5 out of 10 ? 10C5 is the standard answer
 2 years ago

windsylph Group TitleBest ResponseYou've already chosen the best response.0
haha I think that explanation suffices. thank you very much!
 2 years ago
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