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Question
There are 36 members in a student council in a school and the ratio of the number of boys to the number of girls is 3 : 1. How any more girls should be added to the council so that the ratio of the number of boys to the number of girls may be 9 : 5?
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Solution
A ratio of number of boys to the number of girls = 3 : 1
Let the number of boys be 3x and the number of girls be x.
∴ 3x + x = 36
4x = 36
x = 9
∴ Number of boys = 27
Number of girls = 9
Le n number of girls be added to the council.
From given information, we have:
`27/(9 + n) = 9/5`
135 = 81 + 9n
9n = 54
n = 6
Thus, 6 girl are added to the council.
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