The mean of the marks scored by 50 students was found to be 39. Later on it was discovered that a score of 43 was misread as 23. Find the correct mean.
Given,
Mean of marks of 50 students = 39
Sum of marks = 50 × 39 = 1950
It is given that he misread 43 as 23, so,
Correct sum = Sum obtained + (43 – 23) = 1950 + 20 = 1970.
Correct Mean = 
= 
13