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Math Help - 9 coins: 7H and 2T

  1. #1
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    9 coins: 7H and 2T

    p[of tossing nine coins and getting 7H and 2T]
    9C7*.5^9*.5^2

    This equation doesn't yield the correct answer. What is wrong?
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  2. #2
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    Quote Originally Posted by dwsmith View Post
    p[of tossing nine coins and getting 7H and 2T]
    9C7*.5^9*.5^2

    This equation doesn't yield the correct answer. What is wrong?
    Why is 9 your first power of 0.5?
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  3. #3
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    nCr*.5^n*.5^{n-r}
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    Quote Originally Posted by dwsmith View Post
    nCr*.5^n*.5^{n-r}
    Check your formula!!!!
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  5. #5
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    The book sucks don't have one. I had to find that online.
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  6. #6
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    Quote Originally Posted by dwsmith View Post
    The book sucks don't have one. I had to find that online.
    You've either gone to a dodgy site or copied it down incorrectly. Your first power of 0.5 should be r not n.
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