Consider the following page reference string and answer the following questions.

Assume the primary memory is initially unloaded. 1 ,2, 3, 1, 4, 2, 5, 2, 1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2

a. For a FIFO page replacement algorithm with 4 frames, how many page faults are generated? Show work.

b. For a LRU page replacement algorithm with 4 frames, how many page faults are generated? Show work.

c. For the Optimal page replacement algorithm with 4 frames, how many page faults are generated? Show work.

Please help, I have no idea how to do this.