Test series

Question

Consider a system with main memory access time is 150ns and page fault service time is  5 microsecond if one-page fault generated for every 10^3 memory access then what is effective memory access time(in ns)??

 

 

The answer given is 154.85 and the answer I am getting is 4850.15 please verify someone

Comments

given answer is correct....convert 5 microsecond to nano!

Answer 1

Assume that there are 1000 references so there will be 1 page fault,

Avg.memory access time is: ( 999 * 150ns + 1 * 5us ) / 1000 = 154.85 ns

Comments

but how are you so sure that the question is taking main memory as the first where it checks the page. 
It could be cache too???

And if it is cache, then the answer might be

 

please tell me where I am wrong @balchandar reddy san