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Question
The mean of 100 observations is 40. It is found that an observation 53 was misread as 83.
Find the correct mean.
Solution
Given the mean of 100 observations is 40.
`(sumx)/n = barx`
⇒ `(sumx)/n = 40`
⇒ x = 40 x 100
⇒ x = 4000
Incorrect value of x = 4000
Correct value of x = Incorrect value of x - Incorrect observation + correct observation
= 4000 - 83 + 53
= 3970
Correct mean = `("correct value of" sumx)/n`
= `3970/100`
= 39.7
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