Multiple choice

Mean weight of 25 students of a class is 60 kg. If mean weight of first 13 students is 57 kg and that of last 13 students is 63 kg, then the weight of the 13th students is

  1. 60 kg

  2. 40 kg

  3. 30 kg

  4. None of the above
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D Correct answer
AI explanation

The total weight of all 25 students is 25 multiplied by 60, giving a sum of 1500. The sum of the first 13 students is 13 multiplied by 57 (741), and the sum of the last 13 students is 13 multiplied by 63 (819). Adding these two groups gives a combined weight of 1560, which counts the 13th student twice. Subtracting the total class weight from this combined sum yields the weight of the 13th student: 1560 minus 1500 is 60 kg, making the answer none of the above.

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