Problem:
The mean lifetime of all light bulbs produced by a manufacturer is unknown. A sample of 144 bulbs is randomly selected and tested. The average lifetime of this group is measured and found to be 1500 hours with a sample standard deviation of 120 hours.
Required:
Question 1) What is the point estimate for the population mean?
Question 2) Construct the 99% confidence interval estimate for the true population mean.
Solve the given numerical problem and illustrate step by step calculation.