Client servicing process in a cafeteria.
 
Task 1 - duration 1 min, cost 0,01 EUR
Task 2 - duration 2 min, cost 0,02 EUR
Task 3 - duration 3 min, cost 0,03 EUR
Task 4 - duration 4 min, cost 0,04 EUR
Task 2 and Task 3 are mutually exclusive tasks.
The static costs of the instance of the subprocess is 1 EUR.
 
If the subprocess successfully reaches the end, then the Accept payment task will give back 2 EUR for providing the service to the customer (this 2 EUR was modeled as a negative cost; you can offer an alternative way of accounting if you can come up with any alternative ways).
 
The static costs of the waitress (service providing worker) is 0,1 EUR, this applies for each task the waitress performs, regardless of the duration of the task. All waitresses can perform all the tasks.
 
Clients arrive at the start of the main process according to the Weibull distribution, shape = 2 and the scale (average arrival interval)= 6 min
If the client has to wait for 8 minutes for the service, then the client will leave in the middle of the subprocess (the interrupt timer event attached to the subprocess task), in addition to this if the client leaves prematurely then that client will spread unfavourable comments on the cafeteria which will cause additional indirect costs of 4 EUR.
 
What could be the optimal TO BE process and the resource usage (the number of waitresses), if the ordering of the Tasks within the subprocess has to remain the same? Argue based on the simulation results.