An operating system uses shortest remaining time first scheduling algorithm : GATE -2014(3)

An operating system uses shortest remaining time first scheduling algorithm for pre-emptive scheduling of processes. Consider the following set of processes with their arrival times and CPU burst times (in milliseconds):

 Process Arrival Time Burst Time P1 0 12 P2 2 4 P3 3 6 P4 8 5

The average waiting time (in milliseconds) of the processes is _________.

Average waiting time :-$(15+0+3+4) / 4$$=22 / 4 = 5.5$