Someone could help with this exercise please?

a (4 points)Let X1, X2, ..., X\" be a random sample from a population with mean ,u and standard deviation 0. Let 1 1 1 Tn: X X Xn 3 1-! 3 2 t |3 be an estimator for #- Is the estimator biased? If yes, for which values of n it will be unbiased? Compute its variance and comment the result for increasing n