Question

The table below shows the probability distribution of X. Find V(X), that is, the variance of X, to three decimal places.

x	P(X = x)
-1	0.08
2	0.1
6	0.3
10	0.52

Please help I am not sure where to begin and how to solve. This is a business analysis 2372 homework problem I got wrong and guessed on.

Answer 1

Mean = sum of (x*P(x))
= -1 * 0.08 +2*0.1 + 6 * 0.3 + 10 * 0.52
= 7.12

Variance = sum of (x - mean)^2 *P(x)
= (-1-7.12)^2 * 0.08 + (2-7.12)^2*0.1 +( 6-7.12)^2 * 0.3 + (10-7.12)^2 * 0.52
= 12.586