The mean life time of a sample of 400 fluoroscent light bulbs produced by a company is found to be 1,570 hours with a standard deviation of 150 hours. Test the hypothesis that the mean life time of...

Extracted text: The mean life time of a sample of 400 fluoroscent light bulbs produced by a company is found to be 1,570 hours with a standard deviation of 150 hours. Test the hypothesis that the mean life time of the bulbs produced by the company is 1600 hours against the alternative hypothesis that it is greater than 1,600 hours at 1% level of significance.