$(20$ points$)$

Suppose that a disk drive has $5000$ cylinders, numbered $0$ to $4999.$ The drive is currently serving a rquest at cylinder $143,$

and the previous request was at cylinder $125.$ The queue of pending requests, in FIFO order is

$86,1470,913,1774,948,1509,1022,1750,150$

Starting from the current head position, what is the total distance $($in cylinders$)$ that the disk arm moves to satisfy all the

pending requests, for each of the following disk$-$scheduling algorithms.

a$.$ FCFS

b$.$ SSTF

c$.$ SCAN

d$.$ CSCAN