Question

What is the average waiting time for the following processes with non preemptive SJF (Shortes Job First).

Process    Arrival Time        Burst Time

P1        0            8
P2        1            4
P3        2            9
P4        3            5

a.  6.5    

b.  6.75     

c.  7.5     

d  7.75

Answer 1

Gantt Chart for non-preemptive SJF

P1

P2

P3

P4

0                                8                                 12                               17                                26

Here the average waiting time is 0 + (8-1) + (17-2) + (12 - 3) = 31/4 = 7.75