Question

For a group containing 100 observations, the mean and standard deviation are 8 and 10.5 . for 50 observations selected from these 100 observations the mean and standard deviation are 10 and 2 respectively. the standard deviation of the other half is

Answer 1

The mean and standard deviation of a group of 100 observations were found to be 20 and 3, respectively . Later on it was found that three observations were incorrect. Which are recorded by 21,21, and 18 . Find the mean and standard deviation, if the incorrect observations are omitted.

(A)10.10,1.99(B)8.4,5.6(C)3,8(D)20,3.03