Given the following processes with their times and priority (lower number…
2025
Given the following processes with their times and priority (lower number indicates higher priority):
Process | Burst Time | Priority |
P1 | 10 | 3 |
P2 | 1 | 1 |
P3 | 2 | 4 |
P4 | 1 | 5 |
P5 | 5 | 2 |
Which of the following is the value of average waiting time using priority scheduling algorithm?
- A.
9.2
- B.
6.8
- C.
7.6
- D.
8.2
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Correct answer: D
Solution: priority scheduling (lower number = higher priority), assume non-preemptive and all processes arrive at time 0.
Execution order by priority:
P2 (burst 1, priority 1)
P5 (burst 5, priority 2)
P1 (burst 10, priority 3)
P3 (burst 2, priority 4)
P4 (burst 1, priority 5)
Compute waiting times (start time − arrival time; arrival = 0):
P2 starts at 0, waiting time = 0
P5 starts at 1 (after P2), waiting time = 1
P1 starts at 6 (after P2+P5), waiting time = 6
P3 starts at 16 (after P2+P5+P1), waiting time = 16
P4 starts at 18 (after P2+P5+P1+P3), waiting time = 18
Total waiting time = 0 + 1 + 6 + 16 + 18 = 41
Average waiting time = 41/5 = 8.2
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