The central processing unit (CPU) of a microcomputer is a computer chip containing millions of transistors. Connecting the transistors are slender circuit paths only .5 to .85 micron wide. To understand how narrow  these paths are, consider that a micron is a millionth of a meter, and a human hair is 70 microns wide (Compute, 1992). A manufacturer of CPU chips knows that if the circuit paths are not S.85 micron wide, a variety of problems will arise in the chips' performance. The manufacturer sampled four CPU chips six times a day (every 90 minutes from 8:00 A.M. until 4:30 P.M.) for five consecutive days and measured the circuit path widths. These data and MINITAB were used to construct the -chart shown below.

a. Assuming that  = ,3162, calculate the chart's upper and lower control limits, the upper and lower A-B boundaries, and the upper and lower B-C boundaries.

b. What does the chart suggest about the stability of the process used to put circuit paths on the CPU chip? Justify your answer.

c. Should the control limits be used to monitor future process output? Explain