Answer:
a) Round Robin = 21.2 minutes
(b) First -come, First Serve = 19.2 minutes
(c) Shortest job first = 14 minutes
Explanation:
The five job have a time of 10, 6, 2, 4, and 8.
The question doesn't specify the scheduling algorithm, so we will solve for round Robin scheduling algorithm, First Come First Serve and shortest job first scheduling algorithm.
Shortest job first scheduling algorithm execute the job that has the shortest completion time first.
First Come First Serve scheduling algorithm execute the job based on order of arrival.
Round Robin scheduling algorithm execute job based on a given time slice. If the time given is finish and the job hasn't finished, the job is removed and put on the queue while another job enter for execution.
Turnaround time = Completion time - Arrival time
In this case; our arrival time is 0; so turnaround time = completion time.
(a) Round Robin: We were not given quantum time, so we assume quantum time of 1. The sequence of execution will be:
A B C D E | A B C D E | A B D E | A B D E | A B E | A B E | A E | A E | A | A
Average Turnaroud time =
((30-0) + (23-0) + (8-0) + (17-0) + (28-0))/5 = 106/5 = 21.2 minutes
(b) First -come, first served (run in order 10, 6, 2, 4, 8):
A B C D E = ((10-0) + (16-0) + (18-0) + (22-0) + (30-0))/5 = 96/5 = 19.2 minutes
(c) Shortest job first:
C D B E A = ((2-0) + (6-0) + (12-0) + (20-0) + (30-0))/5 = 70/5 = 14 minutes
