Consider the random sample described in problem 9.82 of our text. Consider the statistic U= (1/n) ? Y' . a. Show that U is an unbiased estimator of b. Show that U is a consistent estimator of 0. [ You need not calculate Var Y), just note that it must be finite ] c. Show that U is an efficient estimator of ? . d. Show that U is a sufficient statistic for