Suppose that the access time for cache, memory, hard disc are 10ns, 200ns and 20ms respectively. The hit rate for the cache is 0.95 and main 0.97. a. Compute the effective access time? (include your calculation) b. What is happen if we choose slower cache (250ns) and faster hard disc (10 ms)? C. What is the percentage of increase or decrease of the second configuration over the first one?