A group of people consists of men, women and children. Among them, 20% are men, 30% are women and the rest are children, and their average weights are 50 kg, 40 kg and 30 kg, respectively. The average weight of the group (in kg) is:​

Correct option is A

Given:

20% of the group are men, with an average weight of 50 kg.

30% of the group are women, with an average weight of 40 kg.

The remaining 50% of the group are children, with an average weight of 30 kg.

Solution:

Men make up 20% of the group, so their contribution to the total weight is

20 × 50 = 1000

Women make up 30% of the group, so their contribution to the total weight is

30 × 40 = 1200 kg

Children make up 50% of the group, so their contribution to the total weight is

50 × 30 = 1500 kg

Total average weight = $$\frac{1000 + 1200 + 1500}{100} = \frac{3700}{100} = 37$$​kg.