An assembly$-$line process has six tasks, as listed in the table below: Task time Task $115$ min Task $28$ min Task $317$ min Task $420$ min Task $56$ min Task $624$ min Four workers $($S$1,$ S$2,$ S$3,$ and S$4)$ are staffed to this assembly line, and the assignment of tasks to each worker is as follows: $$ S$1$ does Task $1.$ S$2$ does Tasks $2$ and $3.$ S$3$ does Tasks $4.$ S$4$ does Tasks $5$ and $6.$ For the following questions, we assume that the process is operating at full capacity. $($a$)$ Which worker is the bottleneck of the process? What is the process capacity in $[$units$/$hour$]?$