Final answer:
By summing the completion times of each job scheduled with the FCFS priority rule and dividing by the number of jobs, the average completion time is found to be 7.5 hours.
Step-by-step explanation:
To calculate the average completion time of jobs scheduled using the first come, first served (FCFS) priority rule, we must sum the processing times of the jobs and divide by the number of jobs. In the order received, the jobs and their processing times are: W(4), X(3), Y(2), and Z(1).
The completion time for the first job is 4 hours, for the second job it is 4 + 3 = 7 hours, for the third job it is 7 + 2 = 9 hours, and for the fourth job it is 9 + 1 = 10 hours. To find the average completion time, we add up these completion times (4 + 7 + 9 + 10 = 30 hours), and then divide by the number of jobs, which is 4.
Average completion time = 30 hours / 4 = 7.5 hours.
To find the average completion time using the first come, first served (FCFS) priority rule, we add up the processing times for each job and divide by the number of jobs.
Job W: 4 + 4 = 8
Job X: 3 + 5 = 8
Job Y: 2 + 2 = 4
Job Z: 1 + 1 = 2
The total processing time is 8 + 8 + 4 + 2 = 22 hours. Since there are 4 jobs, the average completion time is 22 / 4 = 5.5 hours.
The correct answer is not listed among the choices provided, but the average completion time is 5.5 hours, which is closest to option D, 5 hours.