A burger joint has on average 9 customers arriving per hour. There is only one employee serving customers and she takes 4 minutes on average to serve a customer. The burger joint is open 10 hours per day and makes a profit of $10 for each burger sold. The staff has a pay rate of $20/hour. Assume a Poisson distribution on the arrival rate of customers and exponential distribution on the service time of the employee.

Q. If customers do not want to spend more than 6 minutes in the burger joint (including waiting and service), how much is the potential profit that the business would lose per day?