Problem $3(1$ point extra credit$)$

$-$ Determine the mean turnaround time for Round$-$Robin $($RR$)$ scheduling for the following processes with time quantum $=20$ ms and all I$/$O requests block for $30$ ms

$-$ Process Q arrives at time $0$ ms $,$ uses $500$ ms total CPU time, blocks for I$/$O after every $50$ ms of CPU time used

$-$ Process R arrives at time $130$ ms $,$ uses $300$ ms total CPU time, blocks for I$/$O after every $20$ ms of CPU time used

$-$ Process S arrives at time $440$ ms $,$ uses $400$ ms total CPU time, blocks for I$/$O after every $50$ ms of CPU time used