The average weight of 8 men increases by 1.5 kg when a man weighing 65 kg is replaced by a new man. What is the weight of the new man?

Explanation

The average rises by 1.5 kg for 8 men, so the total weight rises by 8 × 1.5 = 12 kg. The new man's weight is 65 + 12 = 77 kg.