A computer system has a cache with access time 10 ns, a hit ratio of 80% and average memory access time is 20 ns. Then what is the access time for physical memory?

A computer system has a cache with access time 10 ns, a hit ratio of 8

1.	A computer system has a cache with access time 10 ns, a hit ratio of 80% and average memory access time is 20 ns. Then what is the access time for physical memory?
A.	50 ns
B.	40 ns
C.	30 ns
D.	20 ns
Answer» B. 40 ns