Processes P1, P2 and P3 arrive at 0, 2 and 4 ms with burst times 5, 3 and 1 ms and are scheduled FCFS. What is the average turnaround time?
Correct answer D. 5.33 ms
Explanation
P1 runs 0-5, P2 runs 5-8 and P3 runs 8-9. Turnaround time is completion minus arrival: P1 5, P2 6 and P3 5 ms, which totals 16, so the average is 16 / 3, about 5.33 ms. A common slip is to use completion times without subtracting arrival times. The value 2.33 ms is the average waiting time for the same schedule.
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