$1\mathrm{.}28*0\mathrm{.}05+0\mathrm{.}5=0\mathrm{.}564$

$7)$ You are evaluating bids for suppliers who supply coated metal parts. You need incoming parts to contain between $0\mathrm{.}1\%$ and $0\mathrm{.}25\%$ silver $($these are the specs$).$ One supplier says that they have a process that can produce parts with a mean of $0\mathrm{.}15\%$ silver and a Cp of $1\mathrm{.}38.$

a$.$ What is the supplier$$s process variability?

b$.$ What is the Cpk of that process?

c$.$ Should you work with this supplier? Why or why not?