Consider the following process. The processing time $($sec$/$unit$)$ is given for each worker. b$)$ Customers arrive at this process in the following way: Every $240$ secs two customers arrives at M$1$ starting from time $0$ and every $240$ secs one customer arrives starting from time $100.$ Once a customer arrives at stage $2,$ if both servers are empty, the customer is served at the server with lower processing time. Fill in the below Gantt chart.

Each grid in the following chart represents $\backslash (\backslash$mathbf$\{20\}\backslash$mathbf$\{$~ s e c$\}\backslash ).$ You can extend the below chart as needed.