A quality control analyst for a light bulb manufacturer is concerned that the time it takes to produce a batch of light bulbs is too erratic. Accordingly, the analyst randomly surveys 10 production periods each day for 14 days and records the sample mean and range for each day. Mean (in minutes) Range 58.5 5.1 47.6 7.8 64.3 6.1 60.6 5.7 63.7 6.2 57.5 6.0 55.0 5.4 54.9 6.1 55.0 5.9 62.7 5.0 61.9 7.1 60.0 6.5 58.3 5.9 52.0 5.2 Suppose the analyst constructs an R-chart to see if the variability in production times is in-control. What are the Lower and upper control limits for this chart?
Select one: A. 1.968 - 10.032 B. 0.456 - 11.544 C. 1.338 - 10.662 D. 0 - 11.544
Suppose the analyst constructs an -chart to see if the production process is in-control. What are the Lower and upper control limits for this chart?
A. 56.152 - 59.848
B. 56.59 - 59.41
C. 55.486 - 60.514
D. 56.662 - 59.338
After plotting the -chart and R-chart, is the process out of control?
A. Yes. Because R-chart is out of control.
B. No. It is in control
C. Yes. Because -chart is out of control
D. Yes. Because both charts are out of control