Hypothesis Testing: Mean life for a shipment of lightbulbs
The quality-control manager at a light bulb factory needs to determine whether the mean life of a large shipment of light bulbs is equal to 375 hours. The population standard deviation is 100 hours. A random sample of 64 light bulbs indicates a sample mean life of 350 hours. a. At the 0.05 level of significance, is there eviden