We have two jobs A and B. The execution pattern for A is CPU first IO next, and of B IO first CPU next. Each one needs CPU time of 40mn. The IO time of A is 50% of total execution time of A. Likewise for B. Ignore context switch time or initial program load time (assume that it is zero). Total execution time is defined to be CPU time plus IO time. The unit mn stands for minute.

(a) Serial execution. What is the elapsed time (i.e. turnaround time) of A? What is it of B? Assume that A arrives ahead of B at the same time with B. What is the CPU utilization when the jobs are done? (Express it as a percentage.)

(b) Multiprogramming. Assuming that both arrive at the same time, what is the elapsed time of A? What is it of B? What is the CPU utilization (percentage) ?

(c) Multitasking (timesharing) with slice of 20mn. Multiprogramming is not available. Assuming that both arrive at the same time but A has a slightly faster arrival. What is the elapsed time of A? Of B? CPU utilization (percentage)?

(d) Multitasking (timesharing) with slice of 1mn. Multiprogramming is not available. Assuming that both arrive at the same time but A has a slightly faster arrival. What is the elapsed time of A? Of B? CPU utilization?