Multiple choice

The average of the marks of 25 students in a class, in an examination was calculated to be 19. Later, the teacher realized that the marks of two students were taken as 18 and 19 respectively, instead of 14 and 15 . Find the actual average marks of the class.

  1. 17.43

  2. 16.56

  3. 18.68

  4. 17.65

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The original total marks were 25 × 19 = 475. The error is the difference between the wrongly recorded marks (18+19=37) and the actual marks (14+15=29), which is 8 marks too high. Correct total = 475 - 8 = 467. Actual average = 467/25 = 18.68.