Question

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 1

The correct option is C $40$

Let there be x pupils in the class

Total increase in marks = $x\times \frac{1}{2}=\frac{x}{2}$

$\frac{x}{2}=83-63$ $\Rightarrow x=20\times 2$

$\therefore x=40$