A system uses FIFO policy for system replacement. It has $4$ page frames with no pages loaded to begin with. The system first accesses $100$ distinct pages in some order and then accesses the same $100$ pages but now in the reverse order. How many page faults will occur?
Answer is (A).
When we access the $100$ distinct page in some order (suppose order is $1 2 3$....$100$) then total page fault occurs are $100$. And in last, frame contain the pages $100 99 98 97$. When we reverse the string $(100,99,98....1)$ then first four page will not cause the page fault bcz they already present in frame but the remaining $96$ page will cause $96$ page fault,so total page fault are $100+96=196$.
$Page$ $fault = 100+96(reverse$ $order)=196$