Consider the following table and answer the given question: Process ID CPU…

Concept

FCFS (First-Come-First-Served) is non-preemptive: each process runs to completion in the strict order it arrives, so the completion order is the same as the arrival order.

Round Robin is preemptive: every ready process gets a fixed CPU time slice (the quantum); if its burst is not finished within that slice, it goes to the back of the ready queue and waits for its next turn. The rule that decides ties: when a process arrives at the exact instant another process's quantum expires, the newly arrived process is placed in the ready queue ahead of the process that is being preempted.

Given

Time Quantum = 2

Application: FCFS Scheduling

FCFS executes processes in the order of arrival.

Execution Order

1. P1 arrives first and completes first

2. P2 arrives second and completes second

3. P3 arrives third and completes third

Therefore, FCFS completion order is:

P1 → P2 → P3

Application: Round Robin Scheduling (Quantum = 2)

Step-by-Step Execution

Completion Order

1. 
   P1 completes first
   

2. 
   P3 completes second
   

3. 
   P2 completes last
   

Hence, Round Robin completion order is:

P1 → P3 → P2

Cross-Check

Re-derive the ready-queue snapshots using the tie-break rule from the Concept section. At t=2, P1's first slice ends at the same instant P2 arrives, so the queue becomes [P2, P1] (P2 ahead, since it just arrived). At t=4, P2's slice ends; P3 had already arrived at t=3 (before t=4), so the queue at that point is [P1, P3, P2] -- P1 (already waiting) runs next, then P3 (which arrived before P2 was preempted), then P2. This is exactly why P3 gets the CPU ahead of P2 but not ahead of P1: P3 only jumps ahead of processes that are preempted after it arrives, never processes that were already sitting in the queue before it arrived.

A quick sanity check: the last process finishes at t=15, and the total of all three burst times is 5 + 7 + 3 = 15 -- the CPU never sits idle after t=0, which matches a fully busy schedule.

Final Answer

FCFS: P1, P2, P3
RR: P1, P3, P2