Operating Systems - SJN/Round Robin - turn around time + waiting time 2.(10 pts) a) You are given 4 processes in a batch system that all arrive at time 0 with the following CPU burst times:
        P1 : 35,  P2: 25,  P3: 13, P4: 22.  Assuming there is no context switch overhead, draw a time line chart 
       (Gantt chart) showing when each process executes under each of the following scheduling algorithms:

SJN (Shortest Job Next).    

Round Robin with a quantum of 10. 

Answer - 
https://imgur.com/sLN8Vwr

I don't fully understand how to get the turning or waiting time.

Waiting time I'm assuming is (95+90+88+63)/4 

Turn around time is P1 = 95 - 0 = 95 or 95 - 25 or 95 - 10?
same goes for P2, P3, P4
Turn Around time= Completion time - Arrival Time

and

Waiting time= Turn Around time - Burst time