The mean marks of 100 students were found to be 40. Later on, it was discovered that a score of 53 was misread as 83. Then, the correct mean will be:
39.7
∵ Mean =40
and number of students = 100 [given]
∴ Total marks =40×100
=4000
The correct sum of observations
=4000−(83−53)=4000−30=3970
∴ Correct mean =3970100
=39.7