Consider three processes, all arriving at time zero, with total execution time of $10,20$ and $30$ units respectively. Each process spends the first $20\%$ of execution time doing I$/$O$,$ the next $70\%$ of time doing computation, and the last $10\%$ of time doing I$/$O again. The operating system uses a shortest remaining compute time first scheduling algorithm and schedules a new process either when the running process gets blocked on I$/$O or when the running process finishes its compute burst. Assume that all I$/$O operations can be overlapped as much as possible. For what percentage of does the CPU remain idle?

$1.0\%$

$2.10\mathrm{.}6\%$

$3.30\mathrm{.}0\%$

$4.89\mathrm{.}4\%$