SCENARIO: The process of a firm is as follows. Flow units

enter at the rate of 6 units per minute. All units wait in line for Step A and then do Step A. Then about 40% go to wait in line for step B. When flow units finish Step B,  40% exit.  The remaining 60% go to Step C.  About  50% of the units leaving Step A go to Step C. So, Step C has two flows into it (from B and from A) The remaining units leaving step A  10% go to Step D.   After Step C,  80% of the flow units that went through Step C exit. The rest go to Step D. All flow units going to Step D exit after Step D. So there are  2 flows into Step D (Step A, Step C) On average  2 units are waiting for Step A and it takes  3 minutes to do Step A. On average 1 units are waiting for Step B and it takes 10 minutes to do Step B On average 3 units are waiting for Step C and it takes 3 minutes to do Step C On average 1 units are waiting for Step D and it takes 6 minutes to do Step D