On average, 300 customers arrive per hour at a huge branch of Bank 2. It takes an average of 2 minutes to serve each customer. It costs $10 per hour to keep a teller window open, and the bank...

On average, 300 customers arrive per hour at a huge branch of Bank 2. It takes an average of 2 minutes to serve each customer. It costs $10 per hour to keep a teller window open, and the bank estimates that it will lose $50 in future profits for each hour that a customer waits in line. How many teller windows should Bank 2 open?