Question: A local apparel company is considering adding a new sewing thread supplier. It receives a random sample of 27 spools of thread from the vendor and tests the tensile strength of thread from each spool. The sample average tensile strength is found to be 5 pounds with a sample standard deviation of 0.3 pounds. The population standard deviation is unknown, but the population probability distribution is known to be normal. What is the most appropriate 1% confidence interval for the population mean tensile strength?