The standard deviations of two sets containing 10 and 20 members are 2 and 3 respectively measured from their common mean 5. The S.D for whole set of 30 members is

The standard deviations of two sets containing 10 and 20 members are 2 and 3 respectively measured from their common mean is 5. The standard deviation for the whole set of 30 members is

The mean and standard deviation for a,b and 2 are 3 and 1 respectively,then value of ab is

The sums of the deviations of a set of values measured from 15 and respectively.Find the value of and mean.

The mean and standard deviation of 1,2,3,4,5,6 are

The mean and the standard deviation (s.d.) of five observations are 9 and 0, respectively. If one of the observations is changed such that the mean of the new set of five observations becomes 10, then their s.d. is 0 1 2 4

The mean and standard deviation of a set of n_1, observations are bar x_1 and s_1 ,respectively while the mean and standard deviation of another set of n_2 observations are bar x_2 and s_2, respectively. Show that the standard deviation of thecombined set of (n_1 + n_2) observations is given by S.D.=sqrt((n_1(s_1)^2+n_2(s_2)^2)/(n_1+n_2)+(n_1 n_2(( bar x )_1-( bar x )_2)^2)/((n_1+n_2)^2))

If the mean and the standard deviation of the data 3,5,7,a,b are 5 and 2 respectively, then a and b are the roots of the equation :

If the mean and standard deviation of 5,3,7,a,b are 5 and 2 respectively, then a and b are roots of equation.

If mean of squares of deviations of a set of n observations about - 2 and 2 are 18 and 10 respectively,then standard deviation of this set of observations is