4. (5+5+5 points).Let Y1, Y2, ..., Y.n denote a random sample from the density function given by (P(d)9u)ya_le_y/9= 0 0 is known and (9 is assumed to be positive. a) Find the MLE 6 of 6'. b) Find the expected value and variance of 6. c) Show that 6 is consistent for (9