In Exercise 57, suppose the experimenter had believed before collecting the data that the value of s was approximately .30. If the experimenter wished the probability of a type II error to be .05 when μ = 3.00, was a sample size 50 unnecessarily large?
In Exercise 57
A sample of 50 lenses used in eyeglasses yields a sample mean thickness of 3.05 mm and a sample standard deviation of .34 mm. The desired true average thickness of such lenses is 3.20 mm. Does the data strongly suggest that the true average thickness of such lenses is something other than what is desired? Test using α = .05.