Multiple choice

The average weight of 24 boys was recorded as 62 kgs. If the weight of the teacher was added, the average increased by 1 kg. What was the teacher's weight?

  1. 88 kg.

  2. 92 kg.

  3. 87 kg.

  4. 77 kg.

  5. None of these

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Total weight of 24 boys = 24 × 62 = 1488 kg. With teacher, 25 people average 63 kg, so total = 25 × 63 = 1575 kg. Teacher's weight = 1575 - 1488 = 87 kg. When adding a value to a set, it changes the average by (new value - old average)/(n+1).