Q65

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 time does the CPU remain idle?