A manufacturer of a new, less expensive type of light bulb claims that this product is very well made and even more reliable than the higher priced competitive light bulbs. In order to examine the manufacturer's claim, a random sample of 50 bulbs is tested for length of life. The results are the following.
- Sample Size = 50
- Sample Mean = 5,200 hours
- Sample Standard Deviation = 500 hours
a. Compute the 99% confidence interval for the mean life of this new type of light bulb.
b. Interpret this interval.
c. How many light bulbs should be tested, if the manufacturer wants to be 99% confident of being within 100 hours of the population mean life?