Chapter $3$ Problem solving #$10($p$\mathrm{.}67)$

An automated car wash serves customers with the following serial process: pre$-$treat, wash, rinse, wax, hand dry. Each of these steps is performed by a dedicated machine except for the hand$-$dry step, which is performed manually on each car by one of three workers. The steps of the process have the following processing times:

$\backslash$table$[[$Pre$-$treat,$1$ minute per car$],[$Wash$,5$ minutes per car$],[$Rinse$,2$ minutes per car$],[$Wax$,3$ minutes per car$],[$Hand dry,$8$ minutes per car$]]$

BAIS $3000$ Operations Management $-$ Discussion Class Spr$24$