can someone explain to me how to calculate (ii,iii), thanks

1. Slide 10. . Svstem characteristics - 1 CPU FCFS scheduling algorithm. 1 shared I/O device Context switch time of 0 unit Process Arrival time Service time I/O duration I/O periods PO P1 P2 Table 1 - Process load 5,7 0 4 (i) Draw the Gantt chart to illustrate the CPU, the ready queue, the I'O device and the its associated waiting queue 023i 456 7 8911111 222 222221 22 3 3 3 02 3 4 5 67 9 02 3 4 5 67 8 9 0 12 c p u r e a d y l is t qu e u e (ii) Calculate the turnaround time T,-((21-0) + (11-2) + (18-5)) / 3 = (21 + 9 + 13) / 3 = 43/3-1433 time units (iii) Calculate the waiting time Tw = (8 + 3 + 7) / 3-18/3 = 6.00 time units