Answer for number 11 part 1 and 2. Need asap please

A page replacement algorithm should minimize the number of page faults. Assume we have reference the following memory reference string. 1, 2, 3, 4, 5, 3, 4, 1, 6, 7, 8, 7, 8, 9, 7, 8, 9, 5, 4, 5, 4, 2. How many page faults occur for LRU algorithm for the above reference string with five page frames? Justify your answer. What is the minimum number of page faults for an optimal page replacement strategy for the above reference string with four page frames? Justify your