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Math Help - help with problem solving question

  1. #1
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    Exclamation help with problem solving question

    there are 30 students in a class. they sit at 15 double desks, each one is for 2 students. half of the girls sit with boys. is it possible to make a rearrangement so that half of the boys sit with girls?

    thnx
    justanotherperson

    PS: can you also explain your answer
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  2. #2
    Junior Member
    Joined
    Jul 2009
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    if b stands for boys and g for girls

    notice that

    b+g=30

    also

    b/2+g/2=15

    if you say half of the girls (g/2) sit with boys this means g/2 is a pair number

    but as b/2+g/2=15, b/2 cant be a pair number so its not possible.



    edit:to explain better this

    if you say half of the girls (g/2) sit with boys this means g/2 is a pair number

    this is because g must be pair (cant cut people in half)
    and as half of the girls sits with boys and other half sit together in groups of 2
    g/2 people sit in groups of 2, so g/2 must be also pair
    Last edited by Haytham; September 15th 2009 at 01:37 AM.
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