Question

The mean of 23 observations is 34. If the mean of the first 12 observations is 32, and that of last 12 observations is 38, find the 12th observation.

Answer 1

Mean of 23 observation = 34
Sum of 23 observations = 36×23
= 782

Mean of first 12 observations = 32
Sum of first 12 observations = 32×12
=384

Mean of last 12 observations = 38
Sum of last 12 observations= 38×12
= 456

12 observation = (456+384)-782
12 observation= 840 -782
12 observation = 58