An automobile dealership offers to fill the four tires of your new car with 100% nitrogen for a cost of $25. The dealership claims that nitrogen-filled tires run cooler than those filled with compressed air, and they advertise that nitrogen extends tire mileage (life) by 28%. If new tires cost $50 each and are guaranteed to get 47,000 miles (filled with air) before they require replacement, and the claims are all true, is the dealership's offer a good deal? The cost of tires containing compressed air is $ per mile. (Round to six decimal places.)