Objective: Determine process capability
The sandwich shopâ€^TMs goal I that every sandwich can be completed in
less than 1.5 minutes using the following 20 data times:
1.5364
1.5892
1.4823
1.5610
1.5468
1.5021
1.5065
1.5002
1.5501
1.5423
1.4322
1.5732
1.5923
1.5567
1.5022
1.5345
1.4822
1.4922
1.6004
1.5178

Evaluate the shopâ€^TMs ability to meet the 1.5 minute goal using the following capability measures:

1. What is the Cp? N/A 1.5 becomes the USL as a single sided
2. What is the Cpk?
3. What does the particular Cpk say about the process that other Cpkâ€^TMs may not?
4. What is the Pp? N/A Same reason as Question 1
5. What is the Ppk?

Feedback: The USL is given as 1.5 minutes (you don't compute it). There is no LSL (you can't use 0, since it is a hard limit). Thus you are left with just one spec, an USL of 1.5 minutes. This means you can't compute Cp and Pp (since they require two-sided spec limits).
Secondly, the Cpk is computed using the process standard deviation and only the USL (sprocess is mR-bar/d2 or 0.053/1.128). Next the Ppk is found using the sample standard deviation instead of the process standard deviation and only the USL.