Multiple choice

The average weight of Mack, Tom and Adam was 55 kg and that of Tom, Adam and Jack was 60 kg. If Jack's weight was 56 kg, what was the weight of Mack?

  1. 41 kg

  2. 42 kg

  3. 43 kg

  4. 45 kg

  5. 44 kg
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A Correct answer
Explanation

M+T+A = 55*3 = 165. T+A+J = 60*3 = 180. Subtracting the first from the second: J-M = 180-165 = 15. Since J=56, M = 56-15 = 41.

AI explanation

The total weight of Mack, Tom and Adam is 3 times 55, which equals 165 kg. The total weight of Tom, Adam and Jack is 3 times 60, which equals 180 kg. Since Tom and Adam are common to both groups, the difference in total weight is due to the difference between Mack and Jack. Therefore, Mack's weight is Jack's weight minus the 15 kg difference, giving 56 - 15 = 41 kg.

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