5. If yi's, i = 1, 2, 3, ..., k are k function of random variables calculated from a sample of size n and if each yi distributed about mean 1; with variance of order 1, then prove that k ar ( ) = [ ( x ) of of Var (vi) + cov(yi, yi ) i#j =1 re, f = f(1, V2, .... )k) is any function of y's and possesses partial derivatives