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I absolutely remember learning this is middle school, yet I cannot remember how to solve it for the life of me. Something to do with nCr, maybe? ...

Thanks for any help.

  • 1
    You might want to look at the Binomial Distribution http://en.wikipedia.org/wiki/Binomial_distribution2012-01-30
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    P(at least 8 heads) = P(8 heads) + P(9 heads) + P(10 heads) = (10C8 + 10C9 + 10C10) / 2^102012-01-30
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    Assuming this is NOT homework, $P(\text{At least }8)= P(8) + P(9) + P(10)$ $P(x) \times 2^n= C^n_x = \frac{n!}{x!(n-x)!}$ For A Binomial Distribution $$(P(8) + P(9) + P(10))\times2^{10} = \frac{10!}{8!.2!} + \frac{10!}{9!.1!} + \frac{10!}{10!.0!}$$ $$=\frac{10.9}{2} + 10 + 1 = 56$$2012-02-29

3 Answers 3