Multiple choice

The average weight of 5 boys is 50 kg. If 3 more boys, whose average weight is equal to the weight of the heaviest among the first five boys, join the group, the overall average increases by 3. How much does the heaviest boy among the first five weigh?

  1. 52 kg

  2. 54 kg

  3. 56 kg

  4. 58 kg

  5. 60 kg
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Weighted average: (1/5)(7/8) + (7/20)(1/4) + (2/5)(1/2) + (1/20)(1/2) = 7/40 + 7/80 + 1/5 + 1/40 = (14+7+16+2)/80 = 39/80. 39/80 * M = 172. M = 172 * 80 / 39 = 352.82.

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