Suppose that Y is a random variable with moment generating functionMY (t) = (1/3) + (1/9)e^(5t) + (1/18)e^(t) + (1/2)e^(2t) . Compute the mean of Y in two ways: (a) Compute E[Y] from the derivative of MY(t). (b) Compute the distribution of Y, and then compute the mean of Y directly