1. The process capability measures Cp and Cpk differ because
A) Only one ensures the process mean is centered within the limits
B) Cp values above 1 indicate a capable process; Cpk values above 2 indicate a capable process
C) both are identical
D) Cp values for a given process will always be greater than or equal to Cpk values
E) both A and D
2. 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
D) -, but not R-charts
E) Both p- and c-charts
3. The mean and standard deviation for a process for which we have a substantial history are µ = 120 and If = 2. For the x-bar chart, a sample size of 16 will be used. What is the mean of the sampling distribution?
A) 1/8 (0.125)
4. A manager wants to build 3-sigma control limits for a process. The target value for the mean of the process is 10 units, and the standard deviation of the process is 6. If samples of size 9 are to be taken, the UCL and LCL will be
A) -8 and 28
B) 16 and 4
C) 12 and 8
D) 4 and 16
E) 8 and 12
5. A process that is assumed to be in control with limits of 89 +/- 2 had sample averages of the following? 87.1, 87, 87.2, 89, 90, 89.5, 88.5, and 88. Is the process in control?
B) No, one or more averages exceeded the limits.
C) Not enough information to tell.
D) No, there is a distinguishable trend.
E) No, two or more consecutive points are very near the lower (or upper) limit.
6. The specification for a plastic handle calls for a length of 6.0 inches ± .2 inches. The standard deviation of the process is estimated to be 0.05 inches. What are the upper and lower specification limits for this product? The process is known to operate at a mean thickness of 6.1 inches. What is the Cp and Cpk for this process? Answer: LSL = 5.8 inches, USL = 6.2 inches. Cp is 1.33, and Cpk is .67.