Problem 4: (a) Consider a page reference string: (2 3 5 3 5 1 2). Given three page-frames, how many page replacements will happen with each of the LRU and FIFO algorithms? (b) Extend the reference string in part (a) above with a small number of additional page references to yield an example in which LRU is better than FIFO for the case of three page frames. (c) Now, extend this string in part (a) above with a different sequence of page references to yield an example in which FIFO is better than LRU Siae ha ali n in a rac a nces