Process time at a workstation is monitored using sample mean and range control charts. Six samples of

n

$=$

$10$

observations have been obtained and the sample means and ranges computed $($in minutes$)$: LO$2$

Sample Mean Range

$1.........3\mathrm{.}060\mathrm{.}42$

$2.........3\mathrm{.}150\mathrm{.}50$

$3.........3\mathrm{.}110\mathrm{.}41$

$4.........3\mathrm{.}130\mathrm{.}46$

$5.........3\mathrm{.}060\mathrm{.}46$

$6.........3\mathrm{.}090\mathrm{.}45$

Using the factors in Table $10-3,$ determine the upper and lower limits for sample mean and range control charts.

Is the process in control?