A manufacturer receives an order for fluorescent light bulbs. The order requires that the bulbs have a mean life span of 950 hours. The manufacturer selects a random sample of 25 fluorescent light bulbs and finds that they have a mean life span of 945 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.

1. What is the margin of error for this interval? (round to the nearest hundredth)

2. What is the lower limit of the interval? (Round to the nearest hundredth if necessary)

3. What is the upper limit of the interval? (Round to the nearest hundredth if necessary)

4. Interpret the confidence interval you calculated above.

5. Based on the interval you calculated, is the manufacturer making acceptable light bulbs? (Be sure to justify your answer and explain your reasoning)