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 and R charts. The values for these charts are as follows. The upper and lower control limits for the X chart are $74\mathrm{.}80$ Nm and $72\mathrm{.}37$ Nm$,$ respectively. X is $73\mathrm{.}58$ Nm$.$ R is $1\mathrm{.}66.$ The specification limits are $80$ Nm $+-10.$ Calculate $6$o$,$ Cp$,$ and Cpk$.$ Interpret the values.