A quality inspector took five samples, each with four observations, of the length of time for glue to dry. All values are in minutes. Use this information to create normal distribution graph and three$-$sigma $($i$.$e$.,z=3)$ control chart for the means of future time.

$($Total: $5$ Points$)$

Sample

$\backslash$table$[[$Observation$,,1,2,3,4,5],[1,12\mathrm{.}11,12\mathrm{.}15,12\mathrm{.}09,12\mathrm{.}12,12\mathrm{.}09],[2,12\mathrm{.}10,12\mathrm{.}12,12\mathrm{.}09,12\mathrm{.}10,12\mathrm{.}14],[3,12\mathrm{.}11,12\mathrm{.}10,12\mathrm{.}11,12\mathrm{.}08,12\mathrm{.}13],[4,12\mathrm{.}08,12\mathrm{.}11,12\mathrm{.}15,12\mathrm{.}10,12\mathrm{.}12]]$