1. The quality-control manager at a compact fluorescent light bulb (CFL) factory needs to determine whether the mean life of a large shipment of CFLs is at least 7,500 hours. A random sample of 64 CFLs indicates a sample mean life of 7,250 hours. At the 0.05 significance level, is there evidence that the mean life is less than 7,500 hours?

a.Assume the population standard deviation is 1,000 hours.

b. Assume the sample standard deviation is 1,000 hours