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    Question

    The average age of (x + 4) students of a class is 18 years.

    If the 54 years old class teacher is also included then average age of the class gets increased by two years. Find x% of 300.
    A 36 Correct Answer Incorrect Answer
    B 39 Correct Answer Incorrect Answer
    C 42 Correct Answer Incorrect Answer
    D 45 Correct Answer Incorrect Answer
    E 48 Correct Answer Incorrect Answer

    Solution

    Total age of students = 18(x + 4) years
    According to question,
    [18(x + 4) + 54] = (18 + 2)(x + 4 + 1)
    18x + 72 + 54 = 20x + 100
    20x – 18x = 126 – 100
    x = 13
    So, 13% of 300 = 39

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