Officials at Mountain Airlines are interested in monitoring the length of time customers must wait in line to check in at their airport counter in Reno, Nevada. To develop a control chart, five customers were sampled each day for 20 days. The data, in minutes, are presented in the table below.

a. Construct an R-chart from these data.
b. What does the R-chart suggest about the stability of the process? Explain.
c. Explain why the R-chart should be interpreted prior to the xÌ…-chart.
d. Construct an xÌ…-chart from these data.
e. What does the xÌ…-chart suggest about the stability of the process? Explain.
f. Should the control limits for the R-chart and xÌ…-chart be used to monitor future process output? Explain.
g. Assume the process is under control and construct a capability analysis diagram for the process. Management has specified a USL of 5 minutes.
h. Is the process capable? Justify your answer.
i. If it is appropriate to estimate and interpret Cp for this process, do so. If it is not, explain why.
j. Why didn't management provide a LSL?

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Sample Waiting Time (min.) 3.2 8.4 1. 6.7 1.3 2.2 5.0 4.1 7.9 8.1 .4 3 7.1 3.2 2.1 6.5 3.7 4 4.2 1.6 2.7 7.2 1.4 1.7 7.1 1.6 .9 1.8 6. 4.7 5.5 1.6 3.9 4.0 6.2 2.0 1.2 .9 1.4 1.4 1.1 2.7 4.3 3.8 4.6 3.1 3.8 9.1 2.7 10 2.9 5.3 4.1 9.8 2.7 11 3.2 2.9 4.1 5.6 .8 12 2.4 4.3 6.7 1.9 4.8 13 8.8 5.3 6.6 1.0 4.5 5.9 14 3.7 3.6 2.0 2.7 15 1.0 1.9 6.5 3.3 4.7 16 7.0 4.0 4.9 4.4 4.7 .9 17 5.5 7.1 2.1 2.8 18 1.8 5.6 2.2 1.7 2.1 19 2.6 3.7 4.8 1.4 5.8 20 3.6 .8 5.1 4.7 6.3