The equations to determine the process capability indices Cp and Cpk$.$

USL $-$ LSL

$=$

$60$

Cpk $=$ Cp $(1-$ k$)$

Where:

USL $=$ upper specification limit

LSL $=$ lower specification limit

$=$standard deviation of the process

k$=2($design specification $-$ process average$)$

specification range

R$=$ Mean of the range

R

At the Royal Fairmont hotel$-$casino complex, the time it takes the valet parking service to park a vehicle was measured over the course of several weeks. The manager believes that the target time for parking a vehicle should be between $2$ and $4$ minutes with a target of $3$ minutes. The data gathered had a mean time of $2\mathrm{.}75$ minutes with a standard deviation of $0\mathrm{.}4$ minutes.