Question $6$

A process manager wants to use control charts to control their process. They have

decided that each sample should have $4$ observations. The number of standard

deviations the manager wants to use is $3.$ The manager found that the average range of

the samples is $5.$ The grand average of the samples is $6\mathrm{.}0.$ The standard deviation of the

observations is $2.$ The manager took $20$ samples to use to calculate the control limits$.$

The formulas used to calculate the control limits is:

$UC{L}_x=x_{\frac{?}{\text{b}\text{a}\text{r}}\frac{?}{\text{b}\text{a}\text{r}}}+\frac{zs}{\sqrt[\phantom{2}]{n}}$

In this example, $n=$

No$.$ Please re$-$read equation $9\mathrm{.}2,$ p$.247$