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 ________.

Three processes $$A, B$$ and $$C$$ each execute a loop of $$100$$ iterations. In each iteration of the loop, a process performs a single computation that requires $${t_c}\,\,CPU$$ milliseconds and then initiates a single $${\rm I}/O$$ operation that lasts for $${t_{io}}$$ milliseconds. It is assumed that the computer where the processes execute has sufficient number of $${\rm I}/O$$ devices and the $$OS$$ of the computer assigns different $${\rm I}/O$$ devices to each process. Also, the scheduling overhead of the $$OS$$ is negligible. The processes have the following characteristics:

Process id	tc	tio
A	100 ms	500 ms
B	350 ms	500 ms
C	200 ms	500 ms

The processes $$A, B,$$ and $$C$$ are started at times $$0, 5$$ and $$10$$ milliseconds respectively, in a pure time sharing system (round robin scheduling) that uses a time slice of $$50$$ milliseconds. The time in milliseconds at which process $$C$$ would complete its first $${\rm I}/O$$ operation is __________.

Consider the following set of processes that need to be scheduled on a single $$CPU.$$ All the times are given in milliseconds.

Process Name	Arrival Time	Execution Time
A	0	6
B	3	2
C	5	4
D	7	6
E	10	3

Using the $$shortest$$ $$remaining$$ $$time$$ $$first$$ scheduling algorithm, the average process turnaround time (in $$msec$$) is _______.

Consider the $$3$$ processes, $$P1,$$ $$P2$$ and $$P3$$ shown in the table.

Process	Arrival Time	Time Units Required
P1	0	5
P2	1	7
P3	3	4

The completion order of the $$3$$ processes under the policies $$FCFS$$ and $$RR2$$ (round robin scheduling with $$CPU$$ quantum of $$2$$ time units) are