The quality-control manager at a compact fluorescent light factory needs to determine whether the mean life of a large shipment of CFL is equal to 7500 hours. The population standard deviation is 1,000 hours. A random sample of 64 CFL's indicates a sample mean life of 7250 hours.
A) At the 0.05 level of significance, is there evidence that the mean life is diffrent from 7500 hours?
