please solve (b)

** Using a long rod that has length , you are going to lay out a square plot in which the length of each side is . Thus the area of the plot will be ?. However, you do not know the value of y, so you decide to make n independent measurements X, X21. x of the length. Assume that each X, has mean (unbiased measurements) and variance o?. (a) Show that X2 is not an unbiased estimator for ? (Hint: For any rv Y, E(72) = V(Y) + [E(7)12. Apply this with Y = X.] E(X)= v) + [E(X)12 2 0 + u]2 02 +42 n E(x?) +u? (b) For what value of k is the estimator X2 - ks- unbiased for Hint: Compute E(X2 - ks).) 1-1 k. 71