Multiple choice

When a person weighing 80 kg left a bus, the average weight of the remaining 39 travelers is increased by 100 g. What is the average weight of the remaining 39 travelers?

  1. 80 kg

  2. 82 kg

  3. 84 kg

  4. 86 kg
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let initial average be A for 40 people. Total weight = 40A. After 80kg leaves, total weight = 40A - 80. New average = (40A - 80) / 39 = A + 0.1. 40A - 80 = 39A + 3.9. A = 83.9. The new average is 83.9 + 0.1 = 84 kg.

AI explanation

Let the initial average weight of the 40 travelers be A. When the 80 kg person leaves, the total weight becomes 40A minus 80, and the new average for the 39 remaining travelers is A + 0.1. This creates the equation (40A minus 80) divided by 39 equals A + 0.1. Multiplying by 39 gives 40A minus 80 equals 39A plus 3.9, meaning A equals 83.9 kg. The new average weight of the remaining travelers is 83.9 + 0.1, which equals 84 kg.

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