A production process for the JMF Section is monitored using x$-$bar and R charts.

Ten samples of n $=15$ observations have been gathered with the following results

Sample

Mean

Range

$1$

$251$

$29$

$2$

$258$

$45$

$3$

$233$

$36$

$4$

$275$

$25$

$5$

$234$

$35$

$6$

$289$

$20$

$7$

$256$

$3$

$8$

$265$

$19$

$9$

$246$

$14$

$10$

$323$

$46$

Develop a control chart and plot the means

Is the process in control? Explain