Example 2. The mean of 40 observations was 160. It was detected on rec

1.	Example 2. The mean of 40 observations was 160. It was detected on recheckinwas wrongly copied as 125 for computation of mean. Find the correct mean.that the value of ls
Answer» Incorrect Mean =X’ = 160 No of observations = 40 Incorrect Sum of observations =sum’= 160 x 40 = 6400 Correct sum of observations = = sum’ – 125 +165 = 6400 +40 = 6440 Correct mean = X = 6440/ 40 = 161 I don't understand the incorrect sum...plz explain

Example 2. The mean of 40 observations was 160. It was detected on recheckinwas wrongly copied as 125 for computation of mean. Find the correct mean.that the value of ls

Answer»

Incorrect Mean =X’ = 160

No of observations = 40

Incorrect Sum of observations =sum’= 160 x 40 = 6400

Correct sum of observations = = sum’ – 125 +165

= 6400 +40

= 6440

Correct mean = X = 6440/ 40 = 161

I don't understand the incorrect sum...plz explain