Let Y1, Y2, ..., Yn be i.i.d. draws with mean My and variance of. (a) show that E [(Yi - Y) ] = var(Y;) - 2cov(Y;, Y ) + var (Y). (b) show that cov(Y, Yi) = of/n. (c) Use the results in (a) and (b) to show that E(sy ) = of where sy is the sample variance