Exercise III

Assume we have a demand$-$paged memory. It takes $8$ milliseconds to service a page fault if an empty frame is available or if the replaced page is not modified and $20$ milliseconds if the replaced page is modified. Memory$-$access time is $100$ nanoseconds. Assume that the page to be replaced is modified $85$ percent of the time. What is the maximum acceptable page$-$fault rate for an effective access time of no more than $200$ nanoseconds?