H2 Maths 6.2 - Custom PMF: Finding E(X) and Var(X)

What you will learn

• PMF with values 0, 1, 2, 3 and probabilities 0.1, 0.3, 0.4, k; probabilities sum to 1 so k = 0.2.
• E(X) = sum of x times P(X = x) = 0 + 0.3 + 0.8 + 0.6 = 1.7.
• E(X^2) = sum of x^2 times P(X = x) = 0 + 0.3 + 1.6 + 1.8 = 3.7.