Discrete probability distribution

Question

You are given the following discrete probability distributions:

X        0        1          2            3

P(X)  0.10   0.20     0.30      0.40

A. Compute the mean(expected value)

B. Compute the variance and standard deviation

Please show all the details!

Answer 1

mean = sum of (x * P(x)) for x = 0 to 3.

variance = sum of (x^2 * P(x)) for x = 0 to 3 - mean^2

standard deviation = square root(variance)