Question

    The ratio of the number of boys to the number of girls

    in a school of 640 students, is 5 : 3. If 30 more girls are admitted in the school, then how many more boys should be admitted so that the ratio of boys to that of the girls, becomes 14 : 9.
    A 30 Correct Answer Incorrect Answer
    B 25 Correct Answer Incorrect Answer
    C 15 Correct Answer Incorrect Answer
    D 20 Correct Answer Incorrect Answer

    Solution

    Total student = 640 Ratio boys to girls = 5 : 3 Number of boys = 640 $$\times \ frac {5}{8} = 400 Number of girls = 640 - 400 = 240 Now, Number of girls = 240 + 30 = 270 Let the new admitted boys be x. So, number of boys = 400 + x ratio of boys to that of the girls = 14 : 9 (400 + x) / 270 = 14 / 9 (400 + x) × 9 = (270) × 14 3600 + 9x = 3780 x = 180/9 = 20 20 boys should be admitted.

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