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    Question

    The average of 30 numbers is 55. The average of the

    first 15 numbers is 51 and the average of the last 12 numbers is 56. What is the average of 68, 74 and the remaining 3 numbers?
    A 71 Correct Answer Incorrect Answer
    B 70 Correct Answer Incorrect Answer
    C 72.2 Correct Answer Incorrect Answer
    D 72 Correct Answer Incorrect Answer

    Solution

    Sum of all 30 terms = 30 x 55= 1650 Sum of first 15 terms = 15× 51 = 765 Sum of last 12 terms = 12 x 56 = 672 After removing the first 15 and last 12 terms, there will be 3 terms remaining.   Sum of remaining 3 terms = 1650 (765 +672) = 213 According to the question, 68 and 74 are added to the sum of 3 terms. Thus, the number of total terms becomes 5. Average of 5 terms = (213 +68 + 74)/5 = 71   71 is the average of 68, 74 and the remaining 3 numbers.

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