SOLUTION: If the ratio of boys to girls in a class is 3:5, what fraction of the class are boys?

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Question 414633: If the ratio of boys to girls in a class is 3:5, what fraction of the class are boys?
Found 2 solutions by stanbon, ewatrrr:
Answer by stanbon(75887) About Me  (Show Source):
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If the ratio of boys to girls in a class is 3:5, what fraction of the class are boys?
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Ans: 3/8
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cheers,
Stan H.

Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!


Hi

If the ratio of boys to girls in a class is 3:5

 3/5 = b/g = b/(C-b)

 3(C-b) = 5b

  3C = b(5+3)

  3/8C = b

fraction of the class who are boys is  3/(3+5) = 3/8



For example:  40 in a class:  3/8*40 = 15 boys (40-15 = 25 girls) 

  wihich gives the proportion: 3/5 = 15/25