The average marks of 30 students is 55. If one student who scored 40 is replaced by another who scored 70, what will be the new average?
Show answer & explanation
Correct answer: A
Explanation
Number of students = 30
Initial average = 55
Old score = 40
New score = 70
Initial total sum = 30 × 55 = 1650
New total sum = 1650 − 40 + 70 = 1680
New average = 1680 / 30 = 56