A teacher calculated the average marks of 15 students in a test as 72.4. Later, she found that the marks of one student were wrongly entered as 68.9 instead of 86.3. After correcting the error, what is the correct average mark of the class?
Show answer & explanation
Correct answer: B
Explanation
Given:
Number of students = 15
Incorrect average = 72.4
Incorrectly recorded marks = 68.9
Correct marks = 86.3
Incorrect total marks = 72.4 × 15 = 1086
Correct total marks = 1086 − 68.9 + 86.3 = 1103.4
Correct average = 1103.4 / 15 = 73.56