Case 1) Page fault doesnt occur
Effective time = TLB hit rate * ( TLB access time + Memory access time ) + (1 - TLB hit rate) * ( TLB access time + Page table access time + memory access time )
Effective time = 0.99 ( 20+100) + 0.01*(20+100+100) ---------------( I assumed lvl 1 page table)
Effective time = 121 ns
Case 2) Page fault occurs
Effective time = 121 + 5000000 + 5000000 = 10000121 ns -------------( since the page is dirty we have to write back the result in secondary storage )
So EMAT = 0.0005 * 10000121 + 0.9995 * 121 = 5121 ns