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

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) (Show Source): You can put this solution on YOUR website!
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) (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
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