### A school has 4 sections of chemistry in Class X having 40, 35, 45 and 42 students. The mean marks obtained in Chemistry test are 50, 60, 55 and 45 respectively for the 4 sections. Determine the overall average of marks per student.

A. 50.25 B. 51.25 C. 52.25 D. 53.25 Answer: Option C

### Solution(By Apex Team)

$\begin{array}{l}\text{Average marks}\\ =\left(\Large\frac{50\times40+60\times35+55\times45+45\times42}{40+35+45+42}\right)\\ =\left(\Large\frac{2000+2100+2475+1890}{162}\right)\\ =\Large\frac{8465}{162}\\ =52.25\end{array}$

A. 20
B. 21
C. 28
D. 32

A. 18
B. 20
C. 24
D. 30

A. 10 years
B. 10.5 years
C. 11 years
D. 12 years