If the process average, $\frac{?}{\text{b}\text{a}\text{r}}(\stackrel{}{x})=18\mathrm{.}50cm$; average range, $\frac{?}{\text{b}\text{a}\text{r}}(R)=1\mathrm{.}10cm$; and sample size $=8,$ what are the lower and upper control limits of the $R-$chart?

$18\mathrm{.}090$ to $18\mathrm{.}910cm$

Cannot be computed because the value of $\stackrel{}{x}$ is not given.