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Thread: percent riddle.

  1. #1

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    percent riddle.

    Igor,Stanislav, and Vladimir are walking down the street. They each have a certain whole number of rubles with them(currency). It is known that Igor has 240% of what Vladimir has, and that Igor has 25% of the difference of what Vladimir and Stanislav have. It is known that Igor's money squared is less than 20% of Stanislav's money squared, and that Stanislav has more money than Vladimir's money squared * 2. At least how much does each one have? Can this be solved? First one with an answer+explanation wins.
    Last edited by snakeeyes1000; Aug 17th, 2002 at 05:46 PM.

  2. #2
    Fanatic Member bugzpodder's Avatar
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    looks like its just a system of equations and inequalities. i'll use the first letter in their name to represent each individual's cash, so we have:


    i=2.4v :1
    i=(v+s)/4 :2
    i^2<(s^2)/5 :3
    s>v^2 :4

    1 & 2: 2.4v=(v+s)/4

    2.15v=s/4
    8.6v=s :5

    4 & 5: v<8.6 :6
    5 & 1: i=12s/43

    SBS

    i^2=(12/43)^2*s^2 :7

    3&7: (12/43)^2*s^2<(s^2)/5

    12/43<1/5

    but the inequality is false. so it can't happen.
    Massey RuleZ! ^-^__Cheers!__^-^ Massey RuleZ!


    Did you know that...
    The probability that a random rational number has an even denominator is 1/3 (Salamin and Gosper 1972)? This result is independently verified by me (2002)!

  3. #3
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    Let Igor have i rubles, let Stanislav have s rubles, and let Vladmir have v rubles. (i,s,v) are positive integers.

    i=(240%)*v
    i=(12/5)*v (1)
    i=(25%)*(s-v)
    i=(1/4)*(s-v) (2)
    i^2 < (20%)*(s^2)
    i^2 < (1/5)*(s^2) (3)
    s > 2*(v^2) (4)
    Equate (1) and (2):
    (12/5)*v=(1/4)*s-(1/4)*v
    s=(53/5)*v (5)
    Subst (5) into (4):
    (53/5)*v > 2*(v^2)
    2*(v^2)-(53/5)*v < 0
    10*(v^2)-53*v < 0
    v*(10*v-53) < 0
    Since v > 0, 10*v-53 < 0
    10*v<53
    v<53/10
    Since v is an integer, v</=5
    From (5): s=(53/5)*v,
    Thus, v=5, s=53
    Subst v into (1):
    i=12

    Thus, Igor has 12 rubles, Stanislov has 53 rubles, and Vladmir has 5 rubles.
    Merry Math Making!

  4. #4
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    Bugz:
    i=(v+s)/4 :2
    It is actually i=(s-v)/4, as stated in the problem:

    Igor has 25% of the difference of what Vladimir and Stanislav have
    Merry Math Making!

  5. #5

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    excellent kalkewl8ter. I am very impressed. Bugz, don't worry about it. You show me up in here most of the time anyway.

  6. #6
    Fanatic Member bugzpodder's Avatar
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    oops thats what i get for posting when i usually sleep
    Massey RuleZ! ^-^__Cheers!__^-^ Massey RuleZ!


    Did you know that...
    The probability that a random rational number has an even denominator is 1/3 (Salamin and Gosper 1972)? This result is independently verified by me (2002)!

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