A cafe serving line has a regular coffee urn from which customers serve themselves, as well as one barista who takes orders. On average, 20% of the cafes customers use the self-service system, which also allows for mobile pay using a kiosk, i.e., they skip the barista entirely. Customer arrivals to the cafe follow a Poisson distribution at the rate of 15 persons per hour, and the barista takes about 2 minutes to take down and fulfill each customers order, and this time is exponentially distributed. How much time do you expect to wait in line before you are able to place your drink order with the barista?