Lightbulbs of a certain type are advertised as having an average lifetime of 750 hours. the price of these bulbs is very favorable, so a potential customer has decided to go ahead with a purchase arrangement unless it can be conclusively demonstrated that the true average lifetime is smaller than what is advertised. a random sample of 45 bulbs was selected, the lifetime of each bulb determined, and the appropriate hypotheses were tested using minitab, resulting in the accompanying output.