Posted by annoymous on .
Suppose that the cost of operating a truck in Mexico is cents per mile when the truck runs at a steady speed of v miles per hour. The top speed of the truck is 100 mph. Assume that the driver is paid 10 dollars per hour to drive the truck, and he is to begin a 1600 mile trip.
Write the cost of operating the truck in dollars, as a function of the speed v, for the planned trip .
Write the cost of driver's wages in dollars, as a function of the speed v, for the planned trip .
The total cost of the planned trip, as a function of the speed v, is the sum of the first two costs. Find the most economic speed for the planned trip, i.e., the speed that minimize the total cost is v=

calculus 
drwls,
You left out a formula for cents per mile in terms of speed, v. Operating cost should increase with speed, since mpg goes down. You need that formula to solve the problem.