Operating Systems - Old Questions

3.  Suppose that the disk drive has 50 cylinders, numbered from 0 to 49. The drive currently serving the request at cylinder 20 and the previous request was at cylinder 25. The queue of pending request is 10, 22, 20, 2, 40, 6 and 38 in the order. A seek takes 6 msec per cylinder moved. How much seek time is needed for the following disk-scheduling algorithms?

a.  First-Come, First-Served

b. Shortest Seek Time First

c.  SCAN

d. LOOK