OS Self doubt(Memory management)

Question

] Our CPU is currently idle and the current time is labeled time 0. Four processes arrive to the ready queue at the following times and with the following required run time: 

See image for Ariival time and Process info

Simulate the process scheduling and execution under the FCFS, SJF, and SRTN scheduling algorithms. Indicate each scheduling decision, and calculate the turnaround time for each process. Also calculate the average turnaround time for each scheduling algorithm.

Answer 1

Av. TAT for FCFS= 32.75

Av. TAT for SJF=20.25

Av. TAT for SRTN=15.75

Comments

I do 2-3 times but for SRTN my avg TAT is 19.5

can you describe your answer?

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I also got 19.5