If the sum and sum of squares of `10` observations are `12` and `18` resp., then, The S.D. of observations is :-

Sum of squares of deviation of 10 observations measured from 5 is 17 and sum of squares ofobservations is 170 then mean of observation is

If the mean of 10 observations is 15, then the sum of these observations is

If the algebraic sum of deviations of 20 observation from 30 is 20, then the mean of observation is :

If the men and standards deviation of 100 observations are 50 and 4 respectively.Find the sum of all the observations and the sum of their squares.

If the sum of the deviations of 50 observations from 30 is 50, then the mean of these observations is

If the sum of the deviations of 50 observations from 30 is 50, then the mean of these observations is

If the sum of the deviations of 50 observations from 30 is 50, then the mean of these observations is

If the sum of the deviations of 50 observations from 30 is 50, then the mean of these observations is

The mean of four observations is 3. If the sum of the squares of these observations is 48 then their standard deviation is