μ1. The problem statement, all variables and given/known data Let X1...Xn be a random sample of size n from a normal distribution, Xi~N(μ, sigma^2), and define U = ƩXi and W = ƩXi^2. Find a statistic that is unbiased for δ^2 + μ^2 in terms of U and W. 2. Relevant equations xbar (sample mean) = Ʃxi/n S^2 (sample variance)(Ʃxi^2 + n*xbar^2)/(n-1) 3. The attempt at a solution The real answer is W/n. However I am getting (Wn^2 - U^2)/n^2(n-1) from plugging in the estimators. This worked for the parameter 2μ - 5δ^2. What do I need to do?