Which of the Following Conceptual Definitions of the Cpk Capability

Multiple Choice

Which of the following conceptual definitions of the Cpk capability index is most accurate?

A) The quantity of the upper customer specification minus the lower specification divided by six sigma.
B) The quantity of the upper customer specification minus the lower specification divided by three sigma.
C) The smallest of the quantity of process mean minus the lower customer specification divided by three sigma or the quantity of the upper customer specification minus the process mean divided by three sigma.
D) The difference between the upper customer specification and the upper control limit plus the difference between the lower customer specification and the lower control limit.