The average weight of 21 boys was recorded as 64 kg. If the weight of the teacher was added, the average increased by 1 kg. What was the teacher’s weight?

Answer: Option A

Average weights of 21 boys = 64 kg
Total weights of 21 boys
= 64 × 21
= 1344 kg
The weight of the teacher was added then average increase by 1 kg
⇒ Total weight of teacher and 21 boys
= 65 × 22
= 1430 kg
∴ Weight of teacher
= 1430 - 1344
= 86 kg