An In-Control, Centered Process That Follows a Normal Distribution Has $\mathrm { C } _ { \mathrm { p } } = 0.6667$

Multiple Choice

An in-control, centered process that follows a normal distribution has a $\mathrm { C } _ { \mathrm { p } } = 0.6667$ . How many standard deviations away from the process mean is the upper specification limit?

A) $2 \sigma$
B) $4 \sigma$
C) $\frac { 2 \sigma } { 3 }$
D) $3 \sigma$