Question

the mean of 40 observations was 160. it was detected rechecking the value of 165 was wrongly copied by 125 for computing than mean. find the correct an mean

Answer 1

sorry the correct summation of xi is 6400-125+165= 6440.
which gives mean =6440/40=161.

Answer 2

The mean = sum of all ÷ number of all observation
160 = sum of all ÷ 40
160×40 = 6400
now ATP
6400 - 125 + 165 = 6440÷4
=161
so the correct mean = 161