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Homework Help: Please help solve these ratio problems

  1. Oct 3, 2011 #1
    1. The problem statement, all variables and given/known data


    In each of the following the properties of a compound are given. In each case find A:B:C

    1. 3/8 of A with B and C 1:2

    2. A, B, C are mixed according to the ratios A:B=1:7 and B:C=13:9

    2. Relevant equations



    3. The attempt at a solution

    I just can't seem to solve these two. I got no idea where to even start. Please help.
     
  2. jcsd
  3. Oct 3, 2011 #2

    verty

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    I'll help but show an attempt.
     
    Last edited: Oct 3, 2011
  4. Oct 3, 2011 #3
    1. You know A is 3/8 of the compound, so how much is left over for B and C?
     
  5. Oct 3, 2011 #4
    So that leaves 5/8 of B and C which are in the ratio 1:2.

    Would then be:

    3/8 of A, 5/8 of B and [ 5/8]/2 of C

    ?
     
  6. Oct 3, 2011 #5

    eumyang

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    Not in the way I'm reading your problem. Does the numbers you have "assigned" for B and C, added together, give you 5/8? It does not.

    If you have, say, X and Y in a ratio of 1:2, that means that X has to be 1/3 of the whole, while Y is 2/3 of the whole. Use this hint to figure out what fractions go with B and C if together they are 5/8 (of the compound).
     
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