Let {X1, X2, X3,...} be a sequence of zero-mean dependent random variables such that, 1 ni-j cov (Xi, Xj) = Notice that as |ij| increases, the covariance between X; and X; decreases. Is it true that (Sn/n)c, where Sn = X1 + X + ... + Xn and c is some constant? If yes, find the value of c.