1. The problem statement, all variables and given/known data X1,.....Xn is a random sample from N(μ, σ^2) 2. Relevant equations Estimator of μ maybe? a1 + a2 = a a1 = a2 = a/2 (x-μ)/(σ/√n)~N(0,1) ((x-μ)/σ)^2~Chi square(1) 3. The attempt at a solution I tried to replace μ with its estimator xbar but that gives me 0.