Using a long rod that has length m, you are going to lay out a square plot in which the length of each side is m. thus the area of the plot will be m^2. however, you do not know the value of m, so you decide to make n independent measurements x1, x2, … , xn of the length. assume that each xi has mean m (unbiased measurements) and variance s^2.a. show that x bar 2 is not an unbiased estimator for m^2.b. for what value k is the estimator x bar 2 -ks2 unbiased for m^2?