Let \(U_1,U_2,\ldots ,U_n\) be independent and identically distributed random variables, uniform on \([0,1]\). Let \(U_{1,n}\leq U_{2,n}\leq \cdots \leq U_{n,n}\) denote the order statistics.
(a) Compute the limit distribution of \(Z=n(U_{3,n}-U_{2,n})\).
(b) Show that \(Z_1=n(U_{3,n}-U_{2,n})\) and \(Z_2=n(U_{4,n}-U_{3,n})\) are asymptotically independent.