4. Let X₁, X2, X3 denote a random sample of size n = 3 from a distribution with the Poisson pmf f(x)==-e-5, x = 0, 1, 2, 3, ....
(a) Compute P(X₁ + X₂ + X3 = 1).
(b) Find the moment-generating function of Z = X1 + X2 + X3 ussing the possion mgf of X1. Than name the distribution of Z
(c) find of the probability P(X1 + X2 + X3 = 10) using the result of (b)
(d) if Y = Max {X1, X2, X3} find the probability P (Y<3)