The mean of 150 items was found to be 60. Later on, it was discovered that the values of two items were misread as 52 and 8 instead of 152 and 88 respectively. Find the correct mean.

Question

Philoid · Accepted Answer

Calculated mean of 150 items = 60

Incorrect sum of 150 items = 60×150 = 9000

Correct sum of 150 items = (incorrect sum) - (incorrect items) + (correct items)

= 9000 – (52 + 8) + (152 + 88)

= 9000 – 60 + 240

= 9240 – 60 = 9180

Correct mean =

So, correct mean is 61.2.