Prelim Exam
Below are data to create a Gantt chart, and compute the average waiting time and average
turnaround time using milliseconds as the unit of measurement.
Process Burst Time
P1 21
P2 3
P3 6
P4 6
P5 10
P6 5
A. FCFS
P1 P2 P3 P4 P5 P6
0 21 24 30 38 48
Average turnaround time = (P1 = 0; P2 = 21; P3 = 24, P3 = 30; P4= 36; P5 = 38, P6 = 48) / 6 =
35.66ms ~ 35.7 ms
Average waiting time (FCFS) = (0 + 21 + 24 + 30 + 38 + 48) / 6 = 26.83 ms
B. SJF
P2 P6 P3 P4 P5 P1
0 3 8 14 22 32
Average turnaround time = (32 + 0 + 8 + 14 + 22 + 3) / 6 = 22 ms
Average waiting time (SIF) = (32+ 0 + 8 + 14 + 22 + 3) / 6 = 13.16 ms ~ 13.7 ms
