The data in Table $9$E$\mathrm{.}3$ are temperature readings from a chemical process in $0$C$,$ taken every two minutes. $($Read the observations down, from left.$)$ The target value for the mean is MU$0=950.$

$($a$)$ Estimate the process standard deviation?

$($ Round up to two digits after decimal point, e$.$g$.,11\mathrm{.}69)$

$($b$)$ Set up and apply a tabular CUSUM for this process, using standardized values h$=5$ and k $=(1)/(2).$ Interpret this chart.

The process signals out of control at observation

$.$ The assignable cause occurred after observation

$.$