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problem 7. Lightbulbs of a certain type are advertised as having an average lifetime of 750...

problem 7. 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 50 bulbs was selected, the lifetime of each bulb determined, and the appropriate hypotheses were tested using Minitab, resulting in the accompanying output. (18 points)

 N    Mean  SE Mean        Z      P
50  738.44     5.43    -2.13  0.017

(a) What hypotheses were tested?

(b) What conclusion would be appropriate for a significance level of .05? A significance level of .01?

Math   Statistics-And-Probability   
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