Suppose that $1 and 332 are random samples of observations from a population with mean m and variance .32. Consider the following three point estimators, A, B, C, of m: $31 + 1'2 1'1 + 3$2 331 + 25132 A = B = C = . 2 ' 4 l 3 a) Which of these estimators yields an unbiased estimator of m? Justify your answer. [7 marks] b) Of those that are unbiased, which is the most efficient? Justify your answer. [8 marks]