6.140 Increasing the power. Refer to Example 6.17 (page 375). Suppose the Deely Laboratory wants to make sure the power is at least 80% for μ = 15.30 ppm. It cannot reduce σ, so the options are changing the significance level α and/or sample size n.
(a) With α = 0.01, what sample size n is needed to have at least 80% power?
(b) With α = 0.05, what sample size n is needed to have at least 80% power?
(c) Which of these options do you think the Deely Laboratory should choose? Explain your reasoning.