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Math Help - K-Sided Dice

  1. #1
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    K-Sided Dice

    Hi everyone,

    Looking for a bit of help. If i throw a k-sided dice twice, what is the expected value of their sums. I'm looking for a formula for it including k.

    Thanks
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  2. #2
    Grand Panjandrum
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    Quote Originally Posted by waxandshine View Post
    Hi everyone,

    Looking for a bit of help. If i throw a k-sided dice twice, what is the expected value of their sums. I'm looking for a formula for it including k.

    Thanks
    The expected value of the sum of two RV's is the sum of their expected values.

    So what is the expected value of a single throw of a k-sided die.

    CB
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  3. #3
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    well yeah, but there's no values so it's basically the expected value of one roll times two, but i dont know hot to write a formula for the expected value of one roll
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  4. #4
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    Quote Originally Posted by waxandshine View Post
    well yeah, but there's no values so it's basically the expected value of one roll times two, but i dont know hot to write a formula for the expected value of one roll
    Fair die so probability of each face is 1/k.

    So expected value is:

     <br />
(1)(1/k)+(2)(1/k)+..+(k)(1/k)=(1/k)\sum_{i=1}^k i<br />

    CB
    Last edited by mr fantastic; November 22nd 2008 at 01:30 PM. Reason: Fixed the latex ;)
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