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    The average weight of a group of 20 boys was calculated to be 65 kg and it was later discovered that the weight of a boy was misread as 76 kg instead
    Question

    The average weight of a group of 20 boys was calculated to be 65 kg and it was later discovered that the weight of a boy was misread as 76 kg instead of the correct weight 66 kg. The correct average weight was:

    A.

    65.5 kg

    B.

    64.5 kg

    C.

    66 kg

    D.

    63 kg

    Correct option is B

    Given:

    Number of boys = 20

    Incorrect weight = 76 kg

    Correct weight = 66 kg

    Initial average weight = 65 kg

    Formula Used:

    Total weight =Average× \times​ Number of boys

    Solution:

    Total weight =Average  × \times ​Number of boys

    Total weight = 65× \times​ 20 = 1300

    Correcting the total weight = Total weight - Incorrect weight + Correct weight

    Correcting the total weight = 1300 - 76 + 66 = 1290

    Correct Average = Total correct weight/Number of boys

    Correct Average = 129020\frac{1290}{20}​ = 64.5 kg

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