Let X be a random variable whose possible values x1 x2,... xn occur with probabilities p1, p2,... pn respectively. Then the variance of X, is denoted by var(X) or σx2 = var(X)
= E(X - µ)2 = \(\sum^n_{i=1}\) (xi - µ)2Pi
The non-negative number σx is called the standard deviation of the random variable X.
Another formula to find the variance:
We know that,
