排队论中可以按指数分布的时间间隔产生一个队列，并进入服务时间服从指数分布的服务台，画图得出其到达时间与离开时间，还有每个顾客在系统中的逗留时间(Can produce a queue according to the time interval of exponential distribution in queuing theory, and enter the Business Hours exponentially distributed service station, drawing