B (Statistical Process Control (SPC), difficult)

58. A nationwide parcel delivery service keeps track of the number of late deliveries (more than 30 minutes past the time promised to clients) per day. They plan on using a control chart to plot their results. Which type of control chart(s) would you recommend?

a. - and R-charts

b. p-charts

c. c-charts

d. -, but not R-charts

e. both p- and c-charts

C (Statistical Process Control (SPC), moderate)

59. A run test is used

a. to examine variability in acceptance sampling plans

b. in acceptance sampling to establish control

c. to examine points in a control chart to check for natural variability

d. to examine points in a control chart to check for nonrandom variability

e. none of the above

D (Statistical Process Control (SPC), moderate)

60. Which of the following is true regarding the process capability index C_pk?

a. A C_pk index value of 1 is ideal, meaning all units meet specifications.

b. The larger the C_pk, the more units meet specifications.

c. The C_pk index can only be used when the process centerline is also the specification centerline.

d. Positive values of the C_pk index are good; negative values are bad.

e. None of the above is true.

B (Process capability, moderate)

61. If the C_pk index exceeds 1

a. the AQL must be smaller than the LTPD

b. s must be less than one-third of the difference between the specification and the process mean

c. the x-bar chart must indicate that the process is in control

d. the process is capable of Six Sigma quality

e. the process is characterized as "not capable"

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