### If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55 and 60, then the average marks of all the students is :

A. 54.68 B. 53.33 C. 55 D. None of these Answer: Option A

### Solution(By Apex Team)

Total marks of three batches = 55 × 50 + 60 × 55 + 45 × 60 = 2750 + 3300 + 2700 = 8750 Average $\begin{array}{l}\Large\frac{8750}{55+60+45}\\ =\Large\frac{8750}{160}\\ =\Large\frac{875}{16}\\ =54.68\end{array}$

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