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    Question

    In an Aerobic class, the average age of all the members

    was 54.5 years, 11 members left the class and 7 new members joined. If the average age increased by 3 years and the total age decreased by 140, what was the number of members in the class initially?
    A 30 Correct Answer Incorrect Answer
    B 36 Correct Answer Incorrect Answer
    C 32 Correct Answer Incorrect Answer
    D 40 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Let the original member be x Total age of these members = 54.5x Total age of (x – 4) members = (54.5x – 140) years According to the question, 54.5x – 140 = (x – 4) × 57.5 ⇒ 54.5x – 140 = 57.5x – 230 ⇒ 57.5x – 54.5x = 230 – 140 ⇒ 3x = 90 x = 30

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