Let's assume we know that :
Customer arrive Exponentially with a mean interarrival time of o.5 minutes,
The time an attendant takes to interact with the cudtomerand give them their ice cream cone(s) is modeled with a Triangular distribution with a minimum of 0.4 minutes a most likely tim of 0.9 minutes, and a maximum of 1.5 minutes,
The time the ashier takes to accept payment for the ice cream is also Triangular with a minimum of 0.3 minutes, a most likely time of 0.4 minutes,and maximum of 0.6 minutes,and
The travel time between each process is 15 seconds.