A pupil's marks were wrongly entered as 35 instead of 23. Due to that the average marks for the class got increased by half. The number of pupils in the class is :
Pick one.
A) 30
B) 80
C) 20
D) 25
E) 24

Rationale: let there be x pupils in the class . total increase in marks = ( x * 1 / 2 ) = x / 2 . x / 2 = ( 35 - 23 ) = > x / 2 = 12 = > x = 24 . answer : e
Answer: E