There are 10 I/O bound task and 1 CPU bound task. It is given that time quantum is 10ms. As after every 1 ms each I/O bound task goes for performing I/O for the next 10ms, so 10*(1+0.1)=10*1.1=11ms time is spent by the 10 I/O bound task in CPU computation(including context switch time) and the 1 CPU bound task executes for a time quantum of 10ms, so total time spent by the cpu bound task= 10+0.1=10.1ms
hence out of total 11+10.1= 21.1ms, for (10*1)+10= 20ms CPU is utilized and the remaining time is spent in context switches.
Therefore, CPU utilization= (20/21.1)*100= 94.78%