In 14.3 c, we are asked to calculate the total sek time for each schedule.
We have the formula from 14.3 b i.e seek time (t) = 0.7561 + 0.2439 * sqrt
(L)

Here L is the seek distance in cylinders.

Now for total seek time(T) would be = t1 + t2 + t3 ....+ tn

For FCFS Schedule: 143,86,1470,913,1774,948,1509,1022,1750,130

The total distance = (143-86) + (1470-86) +(1470 -913) + (1774 -913)
+(1774 -948) + (1509 -1022) + (1750-1022 )
                             +(1750-130)
                            = 57 + 1384 +557 +861 + 826 + 561 + 487 + 728 +
1620
                         Lt = 7081 cylinders

Note here that this is the total distance travelled for all the requests. So
when we are asked to find out the total seek time (T) of the schedule  it
would not be equal to just finding out seek time with cylinders 7081 rather
it would be equal to sum of seek times with cylinders of each intermediate
request.
i.e  T !=0.7561 + 0.2439 * sqrt (7081)

Correct answer is
 T= {0.7561 + 0.2439 * sqrt (57)} + {0.7561 + 0.2439 * sqrt (1384)}+ {0.7561
+ 0.2439 * sqrt (557)}+ {0.7561 + 0.2439 * sqrt (861)}
+ {0.7561 + 0.2439 * sqrt (826)}+ {0.7561 + 0.2439 * sqrt (561)}+ {0.7561 +
0.2439 * sqrt (487)}+ {0.7561 + 0.2439 * sqrt (728)}
+ {0.7561 + 0.2439 * sqrt (1620)}

T=65.19 ms

In the same manner you could calculate for other schedules.

Many students gave the correct values but with the wrong formula , for
example

T=0.7561 + 0.2439 * sqrt (7081) = 65.19 ms  and this is wrong if you
calculate.