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    Question

    The average weight of 20 boys is

    48 kg. However, the weights of three boys, originally 46 kg, 44 kg, and 38 kg, were incorrectly recorded as 'k' kg, 'k+2' kg, and 'k−4' kg, respectively. When the correct weights are used, the average weight increases by 0.5 kg. Determine the value of 'k'.
    A 40 Correct Answer Incorrect Answer
    B 45 Correct Answer Incorrect Answer
    C 65 Correct Answer Incorrect Answer
    D 55 Correct Answer Incorrect Answer
    E None of these Correct Answer Incorrect Answer

    Solution

    ATQ, (48 × 20 – k – (k + 2) – (k – 4) + 46 + 44 + 38)/20 = 48 + 0.5 (960 – k – k – 2 – k + 4 + 128)/20 = 48.5 1088 – 3k + 2 = 970 1090 – 3k = 970 3k = 1090 – 970 3k = 120 k = 40

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