Question

A student's marks were wrongly entered as $83$ instead of $63$. Due to that the average marks of the class got increased by half. Find the number of students in the class.

Answer 1

$\begin{array}{c}Lettherebexpupilsintheclass.\\ totalincreaseinmarks=\left(x\times \frac{1}{2}\right)=\frac{x}{2}\\ \frac{x}{2}=\left(83-63\right)\\ \Rightarrow \frac{x}{2}=20\\ \Rightarrow x=40\end{array}$

Hence, this is the answer.