Process ID Arrival time CPU-burst time Priority Number of turns in the round P1 0 160 50 1
P2 1 200 30 2
P3 120 140 8 4
P4 130 160 19 3

A student decided to use Round Robin with time quantum 40 milliseconds. Then, he was asked to take into account processes priorities. So, he decided to give more time quantum turns to processes proportional to its priority and the below table shows number of turns in one round for each process according to his scheme. Of course the ready queue is order according to the arrival time.
Consider the following set of processes, with their priorities and number of turns, arrival times and the CPU-burst times given in milliseconds.
1. Find out the following for both Round Robin with time quantum 40 milliseconds and the modified Round Robin scheduling described above:
a. Draw the Gantt chart. (12 marks)
b. Fill in the above table. (8 marks)
c. Calculate the average waiting time (2 marks)
2. After solving the previous question, analyze the results and in 250-300 words discuss the following with your own words:
a. Do you think that the student's modifications were good for processes with high priorities? How other low priority processes were affected? Support your answer with calculated figures. (6 marks)
b. Discuss any recommendations to improve the student's solution?
(2 marks)