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Math Help - [SOLVED] Calculating required number of wins

  1. #1
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    Jul 2009
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    Post [SOLVED] Calculating required number of wins

    Hi

    I'm making a spreadsheet which will calculate the number of wins required to achieve a given win ratio (expressed as a percentage.) My problem is when someone wins an additional round, they have also played one extra round (and this variance causes the required number of wins to change.)

    The table looks something like this:

    Wins: www
    Rounds Played: xxx
    Win%: yy%

    Required Win%: zz%
    Number of Wins Required: ??

    My question is - What formula would I use to calculate the number of wins required?

    This is quite frustrating since I know it can be done and I'm sure I've done it before, but I can't put my finger on it.
    Last edited by Draco; July 30th 2009 at 12:08 PM. Reason: Added extra information.
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  2. #2
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    Quote Originally Posted by Draco View Post
    Hi

    I'm making a spreadsheet which will calculate the number of wins required to achieve a given win ratio (expressed as a percentage.) My problem is when someone wins an additional round, they have also played one extra round (and this variance causes the required number of wins to change.)

    The table looks something like this:

    Wins: www
    Rounds Played: xxx
    Win%: yy%

    Required Win%: zz%
    Number of Wins Required: ??

    My question is - What formula would I use to calculate the number of wins required?

    This is quite frustrating since I know it can be done and I'm sure I've done it before, but I can't put my finger on it.
    You have:
    The number of wins so far (W)
    The number of games so far (G)
    The percentage of wins required (R)

    And you want to know how many more wins (y) it will take you to reach the winning percentage, right?

    K,

    100*W/G = Percentage wins so far

    100*(W+y)/(G+y) = R
    The y is your only unknown, and incidentally, the answer you'll be looking for...

    100*(W+y) = R*(G+y)
    100*W+ 100*y = R*G + R*y
    100*W - R*G = R*y - 100*y
    (100*W - R*G) = y*(R-100)
    y = (100*W - R*G)/(R-100)

    W,R,G are all known so you just sub them in and solve for y.

    This assumes, of course, that you don't lose any more games...

    Is that what you're looking for?
    It sounds like an odd spreadsheet...
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  3. #3
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    Thank you so much, that answer was spot on.

    Obviously the calculation does not factor in possible losses, but that is not necessary.

    It certainly is a bizarre spreadsheet - It's for an online game which awards titles based on a given ratio for round-type wins. The spreadsheet is designed to calculate the required number of extra rounds needed in-order to achieve the set ratio.
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