Let X1,..., X., be a random sample from a continuous distribution with the density function 10.5(a + 1)(a + 3).x"(1-x2), 00 is an unknown parameter. (a) Find the method of moments estimator of a, ann. (b) Find the maximum likelihood estimator of a, ul. Show that the likelihood func- tion attains its maximum at a râul. = (c) Find the Cramer-Rao lower bound for the variance of an unbiased estimator of a.