Consider the following processes with CPU burst times in milliseconds (table below). The processes are scheduled with Round-Robin scheduling with a time quantum of 4 ms. The waiting time for P₄ is ___ ms.

1. A0
2. B4
3. C12
4. D6

Pick an option to check yourself, or open the answer below.

Show answer & explanation

Correct answer: C. 12

Explanation

All arrive at 0: P1 runs 0–4, P2 4–8, P3 8–12, then P4 runs 12–16 and finishes. P4 waited 12 ms.