Average - General Aptitude

Q1:

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 (1/2). The number of pupils in the class is:

A 10

B 20

C 40

D 73

ANS:C - 40

Let there be x pupils in the class.

Total increase in marks = x x 1 = x
2 2
x = (83 - 63)    x = 20      x= 40.
2 2