If the standard deviation of a variable X is σ, then the standard deviation of the variable is

The sum of the squares deviations for 10 observations for 10 observations taken from their mean 50 is 250. The coefficient of variation is

Let x₁, x₂, ……x_n be values taken by a variable X and y₁, y₂, …….y_n be the values taken by a variable Y such that y_i = ax_i + b, i = 1,2, …….,, n. Then,

If the S.D. of a set of observations is 8 and if each observation is divided by -2, the S.D. of the new set of observations will be

If two variates X and Y are connected by the relation , where a, b, c are constants such that ac < o, then