Consider a cache with four block frames and a fully associative mapping policy. Find the hit ratio for the following Block reference string for replacement policies of FIFO (First-In-FirstOut), LRU (Least Recently Used), and MRU (Most Recently Used). In each case assume the cache is initially empty.

Block Reference String: 0, 1, 2, 3, 4, 0, 1, 5, 0, 1, 2, 3, 4, 5, 4