1. A company has developed a new type of light bulb, and wants to estimate its mean lifetime. A simple random sample of 12 bulbs had a sample mean lifetime of 614 hours with a sample standard deviation of 44 hours. It is reasonable to believe that the population is approximately normal. Find the lower bound of the 95% confidence interval for the population mean lifetime of all bulbs manufactured by this new process.
2. A random sample of 40 videos posted to YouTube was selected. A month later, the number of times that each had been viewed was tabulated. The mean number of viewings was 138 with a sample standard deviation of 568 . Find the upper bound of the 99% confidence interval for the mean number of times videos posted to YouTube have been viewed in the first month.