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Find the ratio of the number of boys to the number of girls

  1. Oct 22, 2004 #1
    my 12 year old bro brought this question to mi and i was dumbfounded...feel so stupid :cry: by logic i know its 2:1 . but i cant explain ..maybe u guys can have a go.

    Class A and Class B have the same number of pupils. The ratio of the number of boys in Class A to the number of boys in Class B is 3:2. The ratio of the number of girls in Class A to the number of girls in Class B is 3:5. Find the ratio of the number of boys to the number of girls in Class A. :rofl: :rofl:
     
    Last edited: Oct 22, 2004
  2. jcsd
  3. Oct 23, 2004 #2
    xA = number of boys in class A
    yA = number of girls in class A
    xB = number of boys in class B
    yB = number of girls in class B

    given,
    xA + yA = xB + yB
    xA/xB = 3/2
    yA/yB = 3/5

    find xA/yA?

    -- AI
     
  4. Oct 23, 2004 #3

    GCT

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    A very simple way to do this is to simply place an arbitrary value (for instance, 10) for a specific variable and go on from there.......plugging in.
     
  5. Oct 26, 2004 #4
    boys to girls

    b1+g1=b2+g2
    b1/b2=3/2
    g1/g2=3/5

    b1/g1+g1/g1=b2/g1+g2/g1
    b1/g1=b2/g1+2/3
    b2/g1=b2/b1 * b1/g1

    so b1/g1= (2/3)(b1/g1) +2/3

    finally b1/g1 =2
     
  6. Oct 27, 2004 #5
    i got 5:6 but i am an idiot
     
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