The access time of a cache memory is 120 ns and that of main memory 900 ns. It is estimated that 80% of the memory requests are for read and remaining 20% for write. The hit ratio for read access only is 0.9. A write-through procedure is used.

(a) What is the average access time of the system considering only memory real cycles?

(b) What is the hit ratio taking in to consideration the write cycle?

(c) What is the average access time of the system for both read and write requests.