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 Pupil’s In The Class Is:

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 (1/2). The Number Of Pupil’s In The Class Is:
a. 8
b. 15
c. 40
d. 55