A pupil's marks were wrongly entered as 85 instead of 45. Due to that the average marks for the class got increased by half. The number of pupils in the class is :
Choose one.
A) 30	B) 80	C) 20	D) 25	E) 26

Rationale: "let there be x pupils in the class . total increase in marks = ( x * 1 / 2 ) = x / 2 . x / 2 = ( 85 - 45 ) = > x / 2 = 40 = > x = 80 . answer : b"
Answer: B