Dispersion (variance)
$$DX = (x_1-EX)^{2}\cdot p_1+(x_2-EX)^{2}\cdot p_2+(x3-EX)^{2}\cdot p3$$
DX - dispersion
EX - mathematical expectation
x1, x2, x3 ... - posible values of event
p1, p2, p3 ... - probabilities of event
EX - mathematical expectation
x1, x2, x3 ... - posible values of event
p1, p2, p3 ... - probabilities of event
Find
It is known that:
= 