An operating system uses shortest remaining time first scheduling algorithm…

An operating system uses shortest remaining time first scheduling algorithm for pre-emptive scheduling of processes. Consider the following set of processes with their arrival times and CPU burst times (in milliseconds):

$\small \begin{array}{|c|c|c|} \hline \textbf{Process} & \textbf{Arrival Time} & \textbf{Burst Time}\\\hline \text{P1} & 0 & 12 \\ \text{P2} & 2 & 4 \\ \text{P3} & 3 & 6 \\ \text{P4} & 8 & 5 \\\hline \end{array}$

The average waiting time (in milliseconds) of the processes is _________.