Problem #$4(10$ pts$)$ Consider a demand$-$paging system with a paging disk that has an average access and transfer time of $20$ milliseconds. Addresses are translated through a page table in main memory, with an access time of $1$ microsecond per memory access. Thus, each memory reference through the page table takes two accesses. To improve this time, we have added a cache that reduces access time to one memory reference, if the page$-$table entry is in the associative memory. Assume that $80$ percent of the accesses are in the associative memory and that, of the remaining, $10$ percent $($or $2$ percent of the total$)$ cause page faults. What is the effective memory access time?