The mean of 100 items was found to be 64. Later on it was discovered that two items were misread as 26 and 9 instead of 36 and 90 respectively. Find the correct mean.
Given,
Mean of 100 items = 64
Sum of items = 100 × 64 = 6400.
It is given that 26 and 9 were misread as 36 and 90, so,
Correct sum = 6400 + (36 – 26) + (90 – 9) = 6400 + 91 = 6491
Correct Mean = 
14