Question

The mean of 5 observations is 12. If the mean of the first 3 is 10, then the mean of the other two is ___ .

Answer 1

Mean of 5 numbers = 12

$Mean=\frac{sumofobservations}{Numberofobservations}$

So, the total sum = mean×total number of observation
= 12×5 = 60

Mean of first 3 is 10

So, the sum total of first 3 would be 10×3 = 30

=>Total sum of rest 2 numbers is 60 - 30 = 30

=>Their mean = $\frac{30}{2}$ = 15