Consider a hypothesis test with H 0 : μ = 20 vs H 1 : μ ≠ 20) at α = 0.05 on mean of a Normal population with unknown variance. If the sample variance is 4 and the true mean is 18.5, then the sample...

Consider a hypothesis test with H₀: μ = 20 vs   H₁: μ ≠ 20) at α = 0.05 on mean of a Normal population with unknown variance. If the sample variance is 4 and the true mean is 18.5, then the sample size required to obtain a power of test at least 80% is close to 15 using an appropriate OC curve.