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    Question

    Average of first 5 numbers is 4 times the average of

    next 4 numbers. If the average of all 9 numbers is 36, find the sum of the last 4 numbers.
    A 45 Correct Answer Incorrect Answer
    B 48 Correct Answer Incorrect Answer
    C 50 Correct Answer Incorrect Answer
    D 54 Correct Answer Incorrect Answer
    E 56 Correct Answer Incorrect Answer

    Solution

    Let the sum of the last 4 numbers be 'n'.
    (sum of first 5 numbers) ÷ 5 = 4 × (n/4)
    ⇒ sum of first 5 numbers = 5n
    Total sum = 5n + n = 6n
    Average = (6n)/9 = 36
    ⇒ 6n = 324
    ⇒ n = 54

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