Suppose a manufacturer claims that the mean lifetime bulb is at least 10,000 hours a quality control inspector tests a sample of 30 light bulbs and finds a mean lifetime of 9,952 hours at a=0.05 is does the evidence suggest that the mean lifetime is less than 10,000 hours ? Assume the population standard deviation is 120 hrs Null hypothesis ? Alternative hypothesis? Test static ? P-value Conclusion? Interpretation: at 5 percent less level of significance there ? Enough evidence to ? The claim that the mean lifetime of the bulbs is at least 10,000 hrs