For this question, you'll develop three different lower and upper control limits for an x$-$bar chart, using $1)$ sample data as the source of standard deviation, $2)$ control chart factors in place of standard deviation, and $3)$ process sigma as the source of standard deviation.

Note how similar $($or different$)$ the x$-$bar chart limits are from one another.

Note also that we only have one way of developing UCL and LCL for the Range chart $($by using control chart factors$).$

A teller at a drive$-$up window at a bank had the following service times $($in minutes$)$ for $20$ randomly selected customers: