The variance of 20 observations is 5. If each observation be multiplied by 2, then find the variance of the resulting observation.

Explanation

We know that if the observations `x_1,x_2,x_3…x_n` has variance var(x). Then observations `a_(x1),a_(x2)….a_(xn)` has variance `a^2` var(x). Thus if variance of 20 observations is 5 and each observation is multiplied by 2, then variance of resulting observation is `2^2xx5=20`