Final answer:
Serve customers based on their arrival time when managing multiple lanes for efficiency and fairness. It takes six minutes on average for three customers to arrive. Model assumptions include single customer arrivals and consistent traffic flow.
Step-by-step explanation:
When handling customers in multiple lanes, the best practice is to serve customers based on their arrival time. This method promotes fairness and efficiency, ensuring that those who arrive first are served first. Using the information provided, on average, one customer arrives every two minutes, so it will take six minutes on average for three customers to arrive when the store first opens. The probability that the next customer will arrive in less than one minute after a customer arrives is low since the average arrival time is two minutes. Similarly, the probability that it takes more than five minutes for the next customer to arrive is also calculable, factoring in the expected arrival rates. It is important to note that this model assumes a single customer arrives at a time and that customer traffic is consistent throughout the day, which may not always be the case in a real-world scenario. Adjustments to handling customer flow might be necessary if customers tend to shop in groups or there are peak hours with increased traffic.