2. Let X1,,Xn be a random sample from Poisson distribution P(),>0. (1) (10 points) Find a complete sufficient statistic for . (2) (15 points) Find the UMVUE of P(X1=0)=exp(). (Hint: I(X1=0) is an unbiased estimator of exp() ). (3) (15 points) Find the CFR lower bound for all unbiased estimators of exp()..