At the drive-through counter of a fast-food outlet, an average of 10 cars waits in line. The manager wants to determine if the length of the line is having any impact on potential sales. Her study reveals that, on average, 6 cars per minute enter the parking lot and look at the length of the line in the drive-through area. Of these 6 cars per minute, on average 25% of the drivers decide that the line is too long and leave without getting into line. Assume that no car that actually chooses to enter the line leaves without service.