A manager at a power company monitored the employee time required to process high-efficiency lamp bulb rebates. A random sample of 40 applications gave a sample mean time of 3.8 minutes and a standard deviation of 1.2 minutes.
(a) Is the claim that μ > 3.5 minutes substantiated by these data? Test with a = .10.
(b) Based on your decision in part (a), what error could you have possibly made? Explain in the context of the problem.