To solve the problem I have used the model below and the following two arrival tables:
Model
Current Arrival Table
New Arrival Table
I have further used Arrival Time Deviation as RandomTriangular(-15,0,30) and Arrival No-Show Probability as 0.10. Using these conditions I get the following result for the current model (1 arrival every 10 minutes)
1 every 10 mins
For new model with 2 arrival every 20 minutes:
2 every 20 mins
For nwe model with 3 arrival every 30 minutes:
3 every 20 mins
From my model runs we can draw conclusion that if the clinic changes the scheduling to 3 every 20 minutes the doctor can see 24 people before 12:30pm.