If mean of squares of deviations of a set of `n` observations about `-2a n d2` are 18 and 10 respectively then standard deviation of this set of observations is 3 (b) 2 (c) 1 (d) None of these

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

If standard deviation of a set of observation is 4 and if each of the observations is divided by 4, then the standard deviation of new set of observations is

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 sum of the squares of deviations for 10 observations taken from their means is 2.5 then write the value of standard deviation.

The sum of deviations of n observations about 25 is 25 and sum of deviations of the same n observations about 35 is -25 . The mean of observations is