Question

Consider the following table of arrival time and burst time for three processes P₀, P₁ and P₂.

Process	Arrival time	Burst Time
P0	0 ms	9 ms
P1	1 ms	4ms
P2	2 ms	9ms

The pre-emptive shortest job first scheduling algorithm is used. Scheduling is carried out only at arrival or completion of processes. What is the average waiting time for the three processes?

(A) 5.0 ms 

(B) 4.33 ms 

(C) 6.33 ms

(D) 7.33 ms

Answer 1

(A) 5.0 ms

Average waiting time = \(\frac{4+11}3\) = 5 ms