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    Question

    Average of 14 observations calculated by a student was

    70 but when he again went through his observations he realised that he took value of three observations as 55, 63 and 51 in place of 74, 84 and 45 respectively and also realised that total observations taken by him was 13. Find the original average of all observations taken by him.
    A 82 Correct Answer Incorrect Answer
    B 78 Correct Answer Incorrect Answer
    C 79 Correct Answer Incorrect Answer
    D 80 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    Sum of 14 observations = 14 × 70 = 980 Original average = {980 + (74 + 84 + 45) - (55 + 63 + 51)}/13 = 1014/13 = 78

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