Studies on a machine that molds plastic water pipe indicate that when it is injecting $27\mathrm{.}23$ mm diameter pipe, the process standard deviation is $0\mathrm{.}28$ mm$.$ The pipe has a specification of $27\mathrm{.}23$ mm plus or minus $1\mathrm{.}64$ mm$.$ What is the process capability index $($Cp$)?$

Question $27$Answer

a$.$

$1\mathrm{.}952$

b$.$

$0\mathrm{.}9762$

c$.$

$5\mathrm{.}857$

d$.$

$3\mathrm{.}905$