1A. Describe the FOUR events in which CPU-scheduling decisions may take place. Consider the following set of processes, arriving at the given times and having the following CPU burst time and priorities: \begin{tabular}{|1|1|1|1|} \hline Process & Arrival Time (ms) & Burst Time $(\mathrm{ms})$ & Priority \hline A & O & 8 & 3 \hline B & 3 & 4 & 1 Thline C & 5 & 7 & 4 1 \hline D & 8 & 3 & 2 \hline \end{tabular) Draw a Gantt chart and calculate average waiting time and turn-around time of each process using SJF, Priority and Round Robin (quantum $3 \mathrm{-ms} $ ) CPU scheduling algorithms. Assume pre-emptive scheduling policy for SJF and Priority scheduling. Consider higher the priority value, lower the priority of the process CS.JG.043