$2.$ Process Capability

From the lecture we learned that natural process variability is the variability that we expect to face in our normal production environment. This natural variability is defined as $+/-3\backslash$sigma from the mean, which is equivalent to $99\mathrm{.}73\%$ of the production $($property of a normally distributed variable$).$Comparing this natural process variability $($represented by $+/-3\backslash$sigma to the specification limits gives us a measure for our $$Process Capability.$$

$2$d$.$ For a given process, the distance between the upper and lower specification limits equals $6\backslash$sigma $,$ and the CPK value is $0\mathrm{.}5.$ What do we know about this process?

Select one:

a$.$ The process is in control.

b$.$ The natural process variability is larger than the distance between the upper and lower specification limits$.$

c$.$ The process is not centered.

d$.$ There is an error because the CPK value cannot be less than $1\mathrm{.}00.$