Question
In a class, the ratio of number of boys to number of
girls is 14:9. If 3 boys joined the class and 3 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 14x and 9x, respectively.
(14x + 3) : (9x − 3) = 5 : 3
Or, 3(14x + 3) = 5(9x − 3)
Or, 42x + 9 = 45x − 15
Or, 3x = 24 ⇒ x = 8
Therefore, number of girls = 9 × 8 = 72
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