Need help on maximizing revenue, maximizing profit word problems!!!

Today, my class was assigned 3 problems as extra credit on our upcoming test. Our teacher warned us that they were kind of difficult. We're not allowed to go to any math professors here on campus and I can't seem to find anyone who knows how to do these problems. They are on Maximizing Profit/ Maximizing Revenue using derivatives and such. If anyone is willing to help please, please let me know! It's just three word problems!

Re: Need help on maximizing revenue, maximizing profit word problems!!!

1. A business that owns or leases 10 or more vehicles may qualify for auto manufacturer fleet purchase incentive. Incentives very from $300 to $7000 on new vehicles. In August 2003, the manufacturer's fleet incentive for a 2004 Chevrolet Cavalier was $1,400. An auto dealer offers an additional discount to fleet buyers who purchase one or more new Cavaliers. To encourage sales, the dealer reduces the after-incentive price of each car by x%, where x is the total number of cars purchased. Assuming that the pre-incentive price of a 2004 Chevrolet Cavalier is$14,400, how many vehicles would the dealer need to sell in order to maximize revenue?

Re: Need help on maximizing revenue, maximizing profit word problems!!!

2. A pool builder makes two types of economy-priced pools: square and circular. He estimates the price of the job by multiplying the perimeter or circumference of the pool (In linear feet) by a fixed price per linear foot. A homeowner wants her pool to have the maximum amount of water surface area for the lowest price possible. Should the homeowner have a square or circular pool built? Explain. (Area of square with a perimeter p is S= 1/16p^2 and the area of a circle with circumference c is A=1/4*pic^2)