The production scheduler of a large manufacturer wants to determine the accuracy of time estimates of an operation set by the industrial engineering department. He randomly selects time and day to...

The production scheduler of a large manufacturer wants to determine the accuracy of time estimates of an operation set by the industrial engineering department. He randomly selects time and day to observe the operation. A sample time record of 115 operation times gave a mean of 4.35 meters and standard deviation of 1.42 meters.

(a) Find 97 per cent confidence interval estimate of the average operation time per component for all components. (b) Find estimated operation time required in hours to produce 2480 components. What is 97 per cent confidence interval of the estimate?