JEUCD 12/1/11

A car rental agency rents 180 cars per day at a rate of 32 dollars per day. For each 1 dollar increase in the daily rate, 5 fewer cars are rented. At what rate should the cars be rented to produce the maximum income, and what is the maximum income?

A certain magical substance that is used to make solid magical spheres costs per cubic foot. The power of a magical sphere depends on its surface area, and a magical sphere can be sold for per square foot of surface area. If you are manufacturing such a s...