### A pupil’s marks were wrongly entered as 83 instead of 63. Due to that the average marks for the class got increased by half. The number of pupils in the class is-

A. 10 B. 20 C. 40 D. 73 Answer: Option C

### Solution(By Apex Team)

Let there be x pupils in the class Total increase in marks \begin{aligned}&=x\times\frac{1}{2}\\ &=\frac{x}{2}\\ &\therefore\frac{x}{2}=(83-63)\\ &\Rightarrow\frac{x}{2}=20\\ &\Rightarrow x=40\end{aligned}

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