The purchasing manager of a certain company needs to estimate the mean life of lightbulbs. He randomly selected 40 lightbulbs from the delivery that indicates a sample average life of 360 hours. The...

ANSWERS SHOULD BE IN 4 DECIMAL PLACES

Extracted text: The purchasing manager of a certain company needs to estimate the mean life of lightbulbs. He randomly selected 40 lightbulbs from the delivery that indicates a sample average life of 360 hours. The supplier stated that the standard deviation is known to be 100 hours. Help the purchasing manager set up a 99% confidence interval estimate of the population mean life of light bulbs in this delivery. d = The mean life of light bulbs is ( hours, hours) with 99% confidence interval