A (Statistical Process Control (SPC), moderate)

48. A manager wishes to build a range chart for a process. The sample size is five, the mean of sample means is 16.01, and the average range is 5.3. From Table S6.1, the appropriate value of D₃ is 0, and D₄ is 2.115. The UCL and LCL for this range chart are

a. 33.9 and 11.2

b. 33.9 and 0

c. 11.2 and 0

d. 6.3 and 0

e. 31.91 and 0.11

c (Statistical Process Control (SPC), moderate) {AACSB: Analytic Skills}

49. Plots of sample ranges indicate that the most recent value is below the lower control limit. What course of action would you recommend?

a. Since there is no obvious pattern in the measurements, variability is in control.

b. One value outside the control limits is insufficient to warrant any action.

c. Lower than expected dispersion is a desirable condition; there is no reason to investigate.

d. The process is out of control; reject the last units produced.

e. Variation is not in control; investigate what created this condition.

E (Statistical Process Control (SPC), difficult)

50. To set -chart upper and lower control limits, one must know the process central line, which is the

a. average of the sample means

b. total number of defects in the population

c. percent defects in the population

d. size of the population

e. average range

A (Statistical Process Control (SPC), moderate)

51. According to the text, the most common choice of limits for control charts is usually

a. ± 1 standard deviation

b. ± 2 standard deviations

c. ± 3 standard deviations

d. ± 3 standard deviations for means and ± 2 standard deviations for ranges

e. none of the above

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