Given that `barx` is the mean and `sigma^(2)` is the variance of `n` observations `x_(1),x_(2),………….x_(n)`. Prove that the mean and variance of the observations `ax_(1),ax_(2),ax_(3),………….ax_(n)` are `abarx` and `a^(2)sigma^(2)` , respectively, `(a!=0)`