The average weight of 8 men is increased by 1.5 kg when one of the men who weighs 65 kg is replaced by a new man. The weight of the new man is:
76 kg
76.5 kg
76.7 kg
77 kg
Explanation:
Let x be the average weight of 8 men (before replacement). Therefore (x+1.5) will be the average weight of 8 men (after replacement)
=> (7 $\times$ x + 68)/8 = x.
=> x = 65.
=> (7 $\times$ x + new)/8 = x + 1.5.
New = (8 $\times$ 65+8 $\times$ 1.5 × 8 $\times$ 65) = 65+12 = 77.