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    Question

    In a class of 40 students, the average weight of the

    boys is 48 kg, and the average weight of the girls is 56 kg. If the overall average weight of the class is 50.4 kg, determine the number of boys in the class.
    A 28 Correct Answer Incorrect Answer
    B 24 Correct Answer Incorrect Answer
    C 18 Correct Answer Incorrect Answer
    D 12 Correct Answer Incorrect Answer
    E 16 Correct Answer Incorrect Answer

    Solution

    Applying allegation method, we get
    Image

    Desired ratio = 5.6:2.4 = 7:3

    Number of boys in the class = 7/10 x 40 = 28

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