Page access time=
(1-page fault)*(Time required to access a page in primary memory) + (page fault) * Miss penalty
We assume page access is Simultaneous !
page fault
rate is (1- hit ratio) = 1- 0.35 = 0.65
Time required to access a page in primary memory is 10 ns as given .
Time to access page in primary memory ( Tp) = (1- 0.65) * 10 = 0.35 * 10 = 3.5 ns.
Time required to access page in secondary memory is the Miss penalty time which is 100 ns as given .
Miss ratio =(1- 0.35)=0.65
Missed pages will be found in secondary memory.
Time to access page in secondary memory ( Ts) = Miss ratio * time for secondary memory
=(1-0.35)*100
=65.0ns
Average time required to access a page is
= Ts+Tp
=65.0ns+3.5ns
=68.5ns
PS :
Read this comment to make everything clear : https://gateoverflow.in/96884/operating-systems-2-29#c125175