Question

a student calculated the value of mean as 20 from 25 observation. it was later discovered at the time of checking that he had copied down two values as 7 and 18 while the correct value will be 13 and 17 . find correct values of arithmetic mean​

Answer 1

Answer:

20.2

Explanation:

The mean is 20 from 25 observations.

So, 20*25= 500 is total data

If previously he has noted 7 and 18 which sum up to 25.

The correct value is 13 and 17 which sum up to 30.

There are 5 more in the data.

Therefore, 500+5=505

So, the new mean is ,

505/25 =20.2