Efficient manufacturing Efficiency experts study the process

Efficient manufacturing: Efficiency experts study the processes used to manufacture items in order to make them as efficient as possible. One of the steps used to manufacture a metal clamp involves the drilling of three holes. In a sample of 75 clamps, the mean time to complete this step was 48.6 seconds. Assume that the population standard deviation is sigma = 8 seconds. Part 1 out of2 N Construct a 99.9% confidence interval for the mean time needed to complete this step. Round to one decimal place, if necessary. A 99.9% confidence interval for the mean is _________

Solution

Confidence Interval: