The counter at the cashier is 4 feet long. Assume a cashier service rate of 80 customers per hour and assume that each tray measures 2 feet in length. What is the probability that an arriving customer will find that the counter is full and she has to just hold her tray for a bit? (The counter length includes both the person paying for a meal and those waiting in line) Enter your answer as a decimal (not a percentage) to three decimal places.