Question

The mean of 10 observation was calculated as 40. It was detected on rechecking that the value of 40 was wrongly copied as 10 . Find the correct mean. ​

Answer 1

Answer:

Mean = (Sum of all observations)/(Number of observations)

or, 40 = (Sum of all observations)/10

So, sum of all observations = 400

But this is incorrect sum, since one observation was copied wrongly.

So, correct sum = Incorrect sum – Incorrect observation + correct observation

= 400 – 15 + 45

= 430

Correct Mean = Correct Sum/ Number of observations

= 430/10

= 43