Consider the following set of processes (arrived at 0ms). The average penalty…
Consider the following set of processes (arrived at 0ms). The average penalty ratio using FCFS scheduling algorithm is :
Answer: 5 — Answer: Average penalty ratio = 5. Explanation and calculations: Order of execution under FCFS (all arrived at 0 ms): P1 (25 ms), P2 (5 ms), P3 (10 ms), P4 (5…
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Correct answer: 5
Answer: Average penalty ratio = 5.
Explanation and calculations:
Order of execution under FCFS (all arrived at 0 ms): P1 (25 ms), P2 (5 ms), P3 (10 ms), P4 (5 ms).
Waiting times: P1 = 0 ms; P2 = 25 ms (after P1); P3 = 30 ms (after P1+P2); P4 = 40 ms (after P1+P2+P3).
Turnaround times (waiting + service): P1 = 25 ms; P2 = 30 ms; P3 = 40 ms; P4 = 45 ms.
Penalty ratio (normalized turnaround) = turnaround / service time: P1 = 25/25 = 1; P2 = 30/5 = 6; P3 = 40/10 = 4; P4 = 45/5 = 9.
Average penalty ratio = (1 + 6 + 4 + 9) / 4 = 20 / 4 = 5.
Note: The original solution inverted the formulas. The correct relation is response ratio = turnaround time / service time (this is the same as the normalized turnaround or penalty ratio). The numeric result (average = 5) is correct.