1. The problem statement, all variables and given/known data The cost of fuel to propel a boat through the water (in dollars per hour) is proportional to the cube of the speed. A certain ferry boat uses $100 worth of fuel per hour when cruising at 10 miles per hour. Apart from fuel, the cost of running this ferry (labor, maintenance, and so on) is $675 per hour. At what speed should it travel so as to minimize the cost per mile traveled? 2. Relevant equations N/A 3. The attempt at a solution I'm having trouble setting up functions to solve this problem. I could do it if I just had some solid functions to work with. The thing that's really getting me is the wording. The problem states: Last time I checked, 10^3 is 1000. What's going on here?