Question

The mean of 100 observations is 40. It is found that an observation 53 was misread as 83.
Find the correct mean.

Answer 1

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