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    Question

    The average of the first three numbers is twice the average

    of the next six numbers. If the average of all nine numbers is 20, then find the sum of the last six numbers.
    A 55 Correct Answer Incorrect Answer
    B 34 Correct Answer Incorrect Answer
    C 46 Correct Answer Incorrect Answer
    D 60 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    ATQ,

    Let the sum of the last six numbers be 'n'.

    So, (sum of the first three numbers) ÷ 3 = 2 × (n/6)

    Or, sum of the first three numbers = 2n

    So, (n + 2n) ÷ 9 = 20

    Or, 3n = 180

    Or, n = 60

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