Question: Problem 3) A manufacturer of flashlight batteries took a sample of 13 batteries from a day’s production and used them continuously until they failed to work. The life of the batteries in hours until failure is:

342, 426, 317, 545, 264, 451, 1049, 631, 512, 266, 492, 562, 298

At the 0.05 level of significance, is there evidence that the mean life of the batteries is more than 400 hours.