3. Let Y1, Y2, . .. , Yn iid Bernoulli(p). Find the moment-generating function for X = Y, + Yz +. .. +Yn . What is the distribution of X? iid 4. Let Y1, Y2, ..., Yn ~ Geometric(p). Find the moment-generating function for W = Y1+ Yz +. . . +Yn . What is the distribution of W? 5. Let Y1, Y2,..., Yn ~ Exponential (B). Find the moment-generating function for V = Y1 + Yz +. . . +Yn . What is the distribution of V? 6. Suppose that X, Y and Z are independent, standard normal random variables. Find the density function of U = x2 + Y2 + Z2. [Use the method of moment generating functions.]