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

    Question

    Average of 15 observations calculated by a student was

    65 but when he again went through his observations he realised that he took value of three observations as 55, 60 and 50 in place of 86, 44 and 75 respectively and also realised that total observations taken by him was 14. Find the original average of all observations taken by him.
    A 70.5 Correct Answer Incorrect Answer
    B 78.5 Correct Answer Incorrect Answer
    C 79.5 Correct Answer Incorrect Answer
    D 72.5 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Sum of 15 observations = 15 × 65 = 975 Original average = {975 + (86 + 44 + 75) - (55 + 60 + 50)}/14 = 1015/14 = 72.5

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