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    Question

    The average weight of 103 notebooks in a box is 10.3 kg.

    When a new notebook is added to the box, the average weight goes up to 10.4 kg. Tell the weight of the new notebook.
    A 20.7 kg Correct Answer Incorrect Answer
    B 20.3 kg Correct Answer Incorrect Answer
    C 20.5 kg Correct Answer Incorrect Answer
    D 20.9 kg Correct Answer Incorrect Answer

    Solution

    Let S be the sum of the weight of notebooks and N is the weight of new notebook. By using the above formula, S/103 = 10.3 S = 103 x 10.3 =1060.9 ----(1) When the new notebook is added, (S + N)/104 = 10.4 S+N=1081.6 N = 1081.6-1060.9 (from equation (1)) N = 20.7

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