Exercise 2 X = {X1, X2. ...,Xn) be a random sample selected from a population with a mean u. Show that the following estimators are unbiased of a and which of them is the efficient 01 = 3X - 2X1, 02 = 5X] - 4X Exercise 3 (X1. X2, X3) be a random sample selected from a population with a mean #. For the observations X, = 1.5, X2 = 2.8, X3 =3.2, find the efficient value as a point estimator # of based on the estimators O, = 1.2X, + 0.6X2 - 0.8X3, 02 = 0.8 X, + 0.6X2 - .4X3