Suppose that a random variable X has a standard normal distribution, and the conditional distribution of a Poisson random variable Y, given the value of X = x, has expectation g(x) = x^2 + 1. Determine E[Y] and Var[Y] I don't understand hov they come to E[Var(Y|X)] =E[X^2 + 1] in the result: Var[Y] = Var[E(Y|X)] + E[Var(Y|X)] = Var[X^2 + 1] + E[X^2 + 1] = Var[X^2] + E[X^2] + 1 Could you please help me with that?
Y|X is Poisson with expectation x^2 + 1 From the tables, the poisson distribution has E[Y|X] = u u = x^2 + 1 So Y|X ~ Poisson(x^2 + 1) From the tables, var(Y|X) = u var(Y|X) = x^2 + 1 So E[var(Y|X)] = E[x^2 + 1]