Multiple choice

The average weight of a group of 25 students increases by 40 g, when a student of 20 kg is replaced by a new student. The weight of the new student is -

  1. $20 kg.$
  2. $20.8 kg.$
  3. $20.4 kg.$
  4. $24 kg.$
  5. $21 kg.$
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Total weight increase = 25 students × 40 g = 1000 g = 1 kg. When replacing a 20 kg student with a new student, the new student must be 1 kg heavier to increase the average by 40 g. Therefore, new student's weight = 20 + 1 = 21 kg. The distractor 20.8 kg might come from incorrectly using 40 g directly instead of multiplying by group size.

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