New Enroll in RBI Grade B New Batch - Starts on May 21

    Question

    The average of 11 observations is 60. If the average of

    first five observations is 58 and that of last five is 56, the sixth observation is
    A 90 Correct Answer Incorrect Answer
    B 110 Correct Answer Incorrect Answer
    C 85 Correct Answer Incorrect Answer
    D 100 Correct Answer Incorrect Answer

    Solution

    Average of 11 observations = 60

    Average of first 5 observations = 58

    Average of last 5 observations = 56


    Total of 11 observations=11×60=660


    Total of first 5 observations=5×58=290


    Total of last 5 observations=5×56=280

    Now, add the total of the first 5 and last 5: 290 + 280 = 570
    Required answer = 660 − 570 = 90 ​

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