A boy’s marks were wrongly entered as 89 instead of 39. Due to this, the class’s average marks increased by half a mark. What is the number of boys in the class?
Show answer & explanation
Correct answer: A
Explanation
Given:
Error: 39 recorded instead of 89 ⇒ Difference = 50
Increase in average = 0.5
According to the formula:
Increase in average = (Total increase / Number)
0.5 = 50 / n
n = 50 / 0.5 = 100