Suppose the true average growth μ of one type of plant during a 1-year period is identical to that of a second type, but the variance of growth for the first type is σ2, whereas for the second type the variance is 4σ2. let x1, , xm be m independent growth observations on the first type [so e(xi) = μ, v(xi) = σ2], and let y1, , yn be n independent growth observations on the second type [e(yi) = μ, v(yi) = 4σ2]. (a) show that the estimator mu hat = δx + (1 − δ)y is unbiased for μ (for 0 < δ < 1, the estimator is a weighted average of the two individual sample means). e(mu hat) = e(δx + (1 − δ)y) = e(x) + e(y) = δμ + μ = (b) for fixed m and n, compute v(mu hat).