Consider a paging system with the page table stored in memory. a$.$ If a memory reference takes $60$ nanoseconds, how long does a paged memory reference take? b$.$ If we add TLBs$,$ and if $80$ percent of all page$-$table references are found in the TLBs$,$ what is the effective memory reference time? $($Assume that finding a page$-$table entry in the TLBs takes $3$ nanoseconds, if the entry is present.$)$ In answering the above two questions, briefly justify your answers