Three models, A$,$ B$,$ and C$,$ will be produced on a mixed$-$model assembly line. Hourly production rate and work content time for model A are $10$ units $\frac{?}{hr}$ and $45\mathrm{.}0$min; for model B are $20$unit$\frac{s}{h}r$ and $35\mathrm{.}0$min; and for model $C$ are $30$unit$\frac{s}{h}r$ and $25\mathrm{.}0$min. Line efficiency is $95\%,$ balance efficiency is $0\mathrm{.}94,$ repositioning efficiency $=0\mathrm{.}93,$ and manning level $=1\mathrm{.}3.$ Determine

a$.$ How many workers and workstations must be on the production line in order to produce this workload.

b$.$ The variable rate launching intervals for models $A,B,$ and $C.$

c$.$ The fixed rate launching interval, and $($b$)$ the launch sequence of models $A,B,$ and $C$ during $1hr$ of production.