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Thread: Prob. question.

  1. #1

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    Hyperactive Member capsulecorpjx's Avatar
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    Prob. question.

    Ok, person A randomly gets a number from 1 to 100.
    Person B randomly gets a number from 1 to 70.

    What are the chances that Person A's number is > Person B's number?

    30% of the time, A will win regardless of what B gets.
    The rest is 50/50? So would it be 30 % + 45%? or 75% of the time A will win?

    [Edit]: It can't be exactly 30%, it must be at least > 50%, I'm guessing its 75%
    Last edited by capsulecorpjx; Sep 1st, 2005 at 12:03 PM.
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  2. #2
    Addicted Member Rassis's Avatar
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    Re: Prob. question.

    I can prove by simulation that P(Xa) > P(Xb) is approximately equal to 0,65 but need some more time to do it analytically or perhaps I leave it to some other colleague in this forum.
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    Addicted Member Rassis's Avatar
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    Re: Prob. question.

    Let me add two more results that might bring some light on the way to the analytical solution:

    If 1 <= Xa <= 100 and 1 <= Xb <= 100, then P(Xa) > P(Xb) = 0,50
    If 1 <= Xa <= 100 and 1 <= Xb <= 50, then P(Xa) > P(Xb) = 0,75
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    Frenzied Member zaza's Avatar
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    Re: Prob. question.

    I don't know where you get the 45% from.
    30% of the time, A wins outright. Of the remaining 70%, it is split 50-50 which is to say 35% each.

    Hence you get 65% in favour of A, 35% to B. Actually, it is slightly less than this because there is also the probability that they get the same number. But close enough.

    zaza

  5. #5

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    Hyperactive Member capsulecorpjx's Avatar
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    Re: Prob. question.

    Quote Originally Posted by zaza
    I don't know where you get the 45% from.
    30% of the time, A wins outright. Of the remaining 70%, it is split 50-50 which is to say 35% each.

    Hence you get 65% in favour of A, 35% to B. Actually, it is slightly less than this because there is also the probability that they get the same number. But close enough.

    zaza
    Thx! Stupid mistakes. I always make them.
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