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 70 clamps, the mean time to complete this step was 42.2 seconds. Assume that the population standard deviation is o = 9 seconds. Round the critical value to no less than three decimal places. Part 1 of 2 (a) Construct a 95% confidence interval for the mean time needed to complete this step. Round the answer to at least one decimal place. A 95% confidence interval for the mean is 6 Su