Question

    There are 15 numbers such that average of first 12

    numbers is 80 while the average of last five numbers is 110. Find the 12th number, if the ratio between 11th and 12th number is 13:7, respectively.
    A 143.5 Correct Answer Incorrect Answer
    B 103.5 Correct Answer Incorrect Answer
    C 133.5 Correct Answer Incorrect Answer
    D 153.5 Correct Answer Incorrect Answer

    Solution

    Sum of first 12 numbers = (12 x 80) = 960 Sum of last 5 numbers = (110 x 5) = 550 Sum of 11th and 12th number = (960 - 550) = 410 So, 12th number = 410 x (7/20) = 143.5

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