Under the FIRST-IN, FIRST-OUT (FIFO) scheduling policy (also called FCFS), three jobs A, B, C arrive at $t=0$ with run times $100, 10, 10$ respectively. What is the AVERAGE TURNAROUND TIME?

1. FIFO runs jobs in arrival order. A first (finishes at $t=100$), then B (at $t=110$), then C (at $t=120$). 2. Turnaround time = completion - arrival. - A: $100 - 0 = 100$ - B: $110 - 0 = 110$ - C: $120 - 0 = 120$ 3. Average: $(100 + 110 + 120)/3 = 330/3 = 110\,\text{ms}$. 4. This is the CONVOY EFFECT: long job A holds up shorter jobs B and C. OSTEP §7.3 explicitly works this example. 5. Option A is wrong arithmetic. Option B drops one job. Option D is just C's turnaround. _Source: OSTEP Ch 7 "Scheduling: Introduction", §7.3 (FIFO) — convoy effect example, p. 2-3._