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 665
hours with a sample standard deviation of 59 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.

Round to the nearest integer. Write only a number as your answer. Do not write any
units.