An Airplane Repair Facility Has a Contract to Repair Cargo

An airplane repair facility has a contract to repair cargo aircrafts for a regional airline. There are 62 planes in the airline company's fleet of planes. Because of the punishing workload, the planes require a considerable amount of maintenance. The repair facility is trying to determine how to schedule the needed repairs. They want to compare the shortest processing time (SPT) rule and the first come, first served (FCFS) rule. Currently, the following planes need repair and are in the repair facility (data given is in the order of plane arrival, only one plane is worked on at a time, and the shop is open 24 hours a day, 7 days a week).
$\begin{array}{|c|c|}\hline \text { Plane } & \text { Estimated repair time } \\\hline \text { A342 } & 4 \text { hours } \\\hline \text { B554 } & 26 \text { hours } \\\hline \text { C222 } & 2 \text { hours } \\\hline \text { D876 } & 16 \text { hours } \\\hline \text { E211 } & 9 \text { hours } \\\hline \text { F887 } & 6 \text { hours } \\\hline\end{array}$
a.In what order should the planes be repaired using the shortest processing time rule (use first letter of plane)?
b.What is the average time (in hours) in the shop using the shortest processing time (SPT) rule?
c.What is the average time (in hours) in the shop using the first come, first served (FCFS) rule?