Question
In a class, the ratio of number of boys to number of
girls is 13:9. If 2 boys joined the class and 6 girls left the class, then the ratio becomes 5:3. Find the actual number of girls in the class.Solution
Let initially the number of boys and girls be 13x and 9x, respectively.
(13x + 2) : (9x − 6) = 5 : 3
Or, 3(13x + 2) = 5(9x − 6)
Or, 39x + 6 = 45x − 30
Or, 6x = 36 ⇒ x = 6
Therefore, number of girls = 9 × 6 = 54Â
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