Consider the 3 processes, P1, P2 and P3 shown in the table. The completion…

FCFS reasoning: processes are served in order of arrival.

• Arrival order: P1 at time 0, P2 at time 1, P3 at time 3.

• Service order and completion times: P1 runs 0–5 (finishes at 5), then P2 runs 5–12 (finishes at 12), then P3 runs 12–16 (finishes at 16).

• FCFS completion order: P1, P2, P3.

Round Robin (quantum = 2) reasoning:

• Start with P1 at time 0.

• Time slices and remaining times (burst remaining after slice):

  • 0–2: P1 runs, remaining 3.

  • 2–4: P2 runs (arrived at 1), remaining 5.

  • 4–6: P1 runs, remaining 1.

  • 6–8: P3 runs (arrived at 3), remaining 2.

  • 8–10: P2 runs, remaining 3.

  • 10–11: P1 runs for its remaining 1 and finishes at time 11.

  • 11–13: P3 runs for its remaining 2 and finishes at time 13.

  • 13–16: P2 runs its remaining 3 and finishes at time 16.

• RR completion order: P1, P3, P2.

Final answer: FCFS completion order is P1, P2, P3; RR (quantum=2) completion order is P1, P3, P2.