Question

What is the average waiting time for the following processes using round robin scheduling with a time quantum of 4 ms?

Process	Burst Time
P1	24
P2	3
P3	3

• A. 5.66 ms
• B. 4 ms
• C. 20 ms
• D. 8.33 ms

Hint:

In RR scheduling, track completion of small bursts and cycle rotations carefully.

Answer 1

The Correct Option is A

Using RR scheduling with 4 ms quantum:
- P1 completes in 6 rounds = 24 ms, wait time = total time - burst - start
- P2 finishes after 1st cycle (4ms), wait = 0
- P3 finishes after 2nd slot (since P1 resumes after P2), wait = 4
Average waiting time = (13 + 0 + 4)/3 = 5.66 ms