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Question
The mean of 200 items was 50. Later on, it was discovered that two items were misread as 92 and 8 instead of 192 and 88.
Find the correct mean.
Solution
Given that the mean of 200 items was 50.
Mean = `sum_x/n`
⇒ 50 = `sum_x/200`
⇒ x = 10,000
Incorrect value of `sum x`= 10,000
correct value of
`sumx` = 10,000 - ( 92 + 8 ) + ( 192 + 88 )
= 10,000 - 100 + 280
= 10,180
Correct mean
= `("correct value of" sumx")/n`
= `10180/200`
= 50.9
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