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The following table shows the processes in the ready queue and time required for each process for completing its job.

Process Time
$P_1$ 10
$P_2$ 5
$P_3$ 20
$P_4$ 8
$P_5$ 15

If round-robin scheduling with 5 ms is used what is the average waiting time of the processes in the queue?

  1. 27 ms
  2. 26.2 ms
  3. 27.5 ms
  4. 27.2 ms

1 Answer

Best answer
5 votes
5 votes

B. 26.2 ms

sequence of execution,

       p1  p2  p3  p4  p5  p1  p3  p4  p5  p3  p5  p3

CT   5    10  15  20  25  30  35  38  43  48  53  58

  CT TT WT
p1 30 30 20
p2 10 10 5
p3 58 58 38
p4 38 38 30
p5 53 53 38

Turnaround Time(TT) = Completion Time - Arrival Time ( every process has 0 AT )

Waiting Time(WT) = TT - Burst Time(BT)

find average of WT thats your answer

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