average PAGE access time OS

In a paged memory the page hit ratio is .35
Time required to access a page in secondary memory is 100 ns.
Time required to access a page in primary memory is 10 ns.

what is the average time required to access a page ?

in what way can i answer this question?

 

Suppose you have 100 accesses. How many will hit primary memory? How many will hit secondary? What is the total time taken by (a) the primary accesses and (b) the secondary accesses? Add them up and divide by 100; that is the average.

 

xpi0t0s gives you the write answer.

 

The exact solution lies here:

Avg. Access time = Page hit ratio ( Primary access time ) + Page miss ratio ( Primary access time + Secondary access time)