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. the correct mean is
Given,
No. of items = 100
Mean of them = 64
Incorrect sum of 100 items = 64 × 100 = 6400.
Correct sum = incorrect sum – (incorrect marks) + correct marks
= 6400 – (26 + 9) + (36 + 90)
6400 – 35 + 126 = 6491.
Correct mean = 64.91.