A pupil 39 s marks were wrongly entered as 83 instead of 63 Due to that the average marks for the cl......

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 :

Let there be x pupils in the class.
Total increase in marks = (x * 1/2) = x/2.
x/2 = (83 - 63) => x/2 = 20 => x = 40.

By: MIRZA SADDAM HUSSAIN