A quality analyst is checking the process capability associated with the production of struts, specifically the amount of torque used to tighten a fastener.

Twenty$-$five samples of size $4$ have been taken.

These were used to create $x-$Bar and $R$ charts.

The values for these charts are as follows:

The upper and lower control limits for the X$-$Bar chart are $74\mathrm{.}80Nm$ and $72\mathrm{.}37Nm,$ respectively.

X$-$Double Bar is $73\mathrm{.}58$ Nm$.$ R$-$Bar is $1\mathrm{.}66.$

The specification limits are $80Nm+-10.$

Calculate $6,Cp,$ and $Cpk.$ Interpret the values. $(30$ pts$.)$