Question:
The mean of 200 items was 50. Later on, it was on discovered that the two items were misread as 92 and 8 instead of 192 and 88. Find the correct mean.
Solution:
The mean of 200 items = 50
Then the sum of 200 items = 200 × 50 = 10,000
Correct values = 192 and 88.
Incorrect values = 92 and 8.
∴ correct sum = 10000 – 92 – 8 + 192 + 88 = 10180
∴ correct mean = 10180/200 = 101.8/2 = 50.9 .