Let Y1,Y2,,Yn be iid N(,2),>0. Both Y and cS are unbiased estimators of , where c=2(n2)n1((n1)/2)

Let YI be iid N(, R), >0. Both Y and cs are unbiased estimators of , where a) prove that for any number b the estimator bY+(l-b)(cS) is an unbiased estimator for X . b) find the value of b that produces the estimator with minimum variance in a) c) show that(X, S ) is a sufficient statistics for .