Question

    The number of students in class IX and class X is 42 and

    45, respectively. The ratio of the number of boys to girls in classes is IX and X is 9: 5 and 8: 7, respectively. What is the difference between the total number of boys and the total number of girls in both the classes taken together?
    A 11 Correct Answer Incorrect Answer
    B 12 Correct Answer Incorrect Answer
    C 17 Correct Answer Incorrect Answer
    D 15 Correct Answer Incorrect Answer

    Solution

    Number of boys in class IX = 42 × (9/14) = 27 Number of girls in class IX = 42 × (5/14) = 15 Again, Number of boys in class X = 45 × (8/15) = 24 Number of girls in class X = 45 × (7/15) = 21 Total of boys in two classes = 27 + 24 = 51 Total of girls in two classes = 15 + 21 = 36 Difference = 51 - 36 = 15 ∴ The difference between the total number of boys and the total number of girls in both the classes taken together is 15.

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