A group of people contains men, women and children. If 40% of them are men, 35% are women and rest are children. and their average weights are 70 kg,60 kg and 30 kg, respectively. The average weight of the group is:

Correct option is C

Given:
Percentage of Men = 40%
Percentage of Women = 35%
Percentage of Children = 25%
Average Weight of Men = 70 kg
Average Weight of Women = 60 kg
Average Weight of Children = 30 kg
Formula Used:
The average weight of the group is given by:
​$$\text{Average Weight} = \frac{(P_m \cdot W_m) + (P_w \cdot W_w) + (P_c \cdot W_c)}{100}$$​​
where:
$$P_m, P_w, P_c$$​are the percentages of men, women, and children respectively.
$$W_m, W_w, W_c$$​ are the average weights of men, women, and children respectively.
Solution:
​$$P_m = 40\%, P_w = 35\%, P_c = 25\%$$​​
​$$\text{Average Weight} = \frac{(40 \cdot 70) + (35 \cdot 60) + (25 \cdot 30)}{100}\\\text{Average Weight} = \frac{(40 \cdot 70) + (35 \cdot 60) + (25 \cdot 30)}{100}\\\text{Average Weight} = 56.50 \text{ kg}\\$$​​