Question
In a class, the ratio of number of boys to number of
girls is 8:5. If 1 boy joined the class and 2 girls left the class, then the ratio becomes 7:4. Find the actual number of girls in the class.Solution
Let initially the number of boys and girls be 8x and 5x, respectively.
(8x + 1) : (5x − 2) = 7 : 4
Or, 4(8x + 1) = 7(5x − 2)
Or, 32x + 4 = 35x − 14
Or, 3x = 18 ⇒ x = 6
Therefore, number of girls = 5 × 6 = 30Â
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