X 0 1 2 3 4 P(x) 0.08 0.22 0.34 0.21 0.15 1. Yes, this is a valid probability distribution because the sum of all the given P(x) is equal to 1. P(x) = P(0) + P(1) + P(2) + (P(3) + P(4) = 0.08 + 0.22 + 0.34 + 0.21 + 0.15 = 1 2. To get the probability of getting C or Higher, add P(2), P(3), and P(4). P(2 or 3 or 4) = P(2) + P(3) + P(4) = 0.34 + 0.21 + 0.15 = 0.7