Let X have a Poisson distribution with a variance of 3.5. Find P(X <= 8) Solution V(X) = ? = 3.5 P(X = 8) = P(x=0) + P(x=1) + P(x=2) + P(x=3) + P(x=4) + P(x=5) + P(x=6) + P(x=7) + P(x=8) P(X = 8) = (e-3.5*3.50)/0! + (e-3.5*3.51)/1! + ... + (e-3.5*3.58)/8! P(X = 8) = 0.990126.