GATE 1996 CPU Scheduling algo completion time RR

Four jobs to be executed on a single processor  system arrive at time 0+ in the order A, B, C, D.  Their burst CPU time requirements are 4,1, 8, 1  time units respectively. The completion time of  A under round robin scheduling with time slice  of one time unit is  

(a) 10 

(b) 4  

(c) 8 

(d) 9

Sol. 

As ‘A’ was in CPU from 0 to 9.

So completion time of ‘A’ is 9.