Question

The mean of 200 items was 50. Later on, it was discovered that the two items were misread
as 92 and 8 instead of 192 and 88. Find the correct mean.

Answer 1

The mean of 200 items = 50
Then the sum of 200 items = 20050 = 10, 000
Correct values = 192 and 88

Incorrect values = 92 = 8

  ∴ Correct sum =10000 - 92 - 8 +192 + 88 = 10180

  ∴ Correct mean = `10180/200 = 50 .9` 

                         =  `10180/2 = 50 .9`