9. Processor utilization is the percentage of time that the processor spends doing useful work (such as executing arithmetic instructions). Assume that an individual process in a system spends about 75% of its time waiting for I/O operations to be completed (not useful work). When Process X is waiting on I/O, the processor can execute Process Y. For both parts (a) and (b), show your work. (1 point) a. What is the processor utilization if four processes are loaded into memory? b. How many processes should we keep in memory if we want processor utilization to be at least 85%? Virtual Memory 10. Answer the following questions using this virtual memory table. (1 point) Physical Memory Address Allocated To: Virtual Memory Address 0 - 15 0 - 15 Program A 16 - 31 0 - 15 Program B 32-47 16 - 31 Program A 48 - 63 32-47 Program A 64 - 79 ? Program B a. What range of addresses should replace the question mark in the above table? b. Program A wants to access a variable stored in virtual address 35. What physical address is this variable stored in