Consider the following process flow chart, with resources and processing times given below each activity.

machine a $-3$ min$/$units; machine b $4$min $/$unit ; machine $23$min$/$unit

$($a$)$ What is the flow time?

$($b$)$ What is the process capacity?

$($c$)$ What is the utilization of Activity $3$

$($d$)$ Which Activity is the bottleneck