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    Question

    The average of sixty numbers is 70 while the average of

    first thirty numbers and last thirty numbers is 75 and 85, respectively. Find the thirtieth term.
    A 600 Correct Answer Incorrect Answer
    B 520 Correct Answer Incorrect Answer
    C 640 Correct Answer Incorrect Answer
    D 785 Correct Answer Incorrect Answer

    Solution

    ATQ,

    Sum of sixty numbers = (60 × 70) = 4200

    Sum of the first thirty numbers = (30 × 75) = 2250

    Sum of the last thirty numbers = (30 × 85) = 2550

    So, thirtieth term = 2250 + 2550 - 4200 = 600

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