The average weight of a certain number of students in a class is 68.5 kg. If 4 new students having weights 72.2 kg, 70.8 kg, 70.3 kg and 66.7 kg join the class, then the average weight of all the students increases by 300 g. The number of students in the class, initially, is:

A. 21

B. 16

C. 11

D. 26

Answer: Option B

Solution(By Examveda Team)

$$\eqalign{ & {\text{Let total students}} = x \cr & \frac{{68.5x + 280}}{{x + 4}} = 68.8 \cr & 68.5x + 280 = 68.8x + 275.2 \cr & 0.3x = 4.8 \cr & x = 16 \cr} $$