Question: A manufacturer receives an order for fluorescent light bulbs. The order requires that the bulbs have a mean life span of 500 hours. The manufacturer selects a random sample of 16 fluorescent light bulbs and finds that they have a mean life span of 495 hours with a standard deviation of 15 hours. Test to see if the manufacturer is making acceptable light bulbs. Use a 95% confidence level. Assume the data are normally distributed.

Use the notation: (lower end, upper end) for your confidence interval. That is, of the form (23.2, 27.7). Greater than and less than signs will not work properly.