Note 2: We can use the probability distribution to calculate probabilities for associated events.
examples: Let X = number of heads observed when flipping a fair coin.
P(X ≥ 2) = P(X = 2) + P(X = 3) + P(X = 4)
= 6/16 + 4/16 + 1/16 = 11/16
P(X < 4) = 1 – P(X ≥ 4) = 1 – 1/16 = 15/16