The average mark in an exam was 60. Due to some assessment errors, the marks of 115 students had to be changed from 85 to 50 each, and the new average is 55. The total number of students who appeared in the examination was:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 805.
Let total students = x
Original total marks = 60x
Marks reduced per student = 85 - 50 = 35
Total reduction = 115 × 35 = 4025
New total marks = 60x - 4025
New average = 55 → (60x - 4025) / x = 55
60x - 4025 = 55x
→ 5x = 4025
→ x = 805