7. An apple orchard now has 80 trees per hectare and the average yield is 400 apples per tree. For each additional tree planted per hectare the average yield per tree is reduced by approximately four apples. How many trees per hectare will give the largest crop of apples? 8. Time to Travel advertises a package plan for an Arizona vacation. The fare for the ight is $400/person plus $8/person for each unsold seat on the plane. The plane holds 120 passengers and the flight will be cancelled if there are fewer than 25 passengers. What number of passengers will maximize revenue? 9. An open-topped storage box with a square base has a capacity of 5 m3. The material for the sides cost $1 .60/m2, while the material for the bottom costs $2.00/m2. Find the dimensions that will minimize the cost of making the box. 10. A rectangular piece of paper with perimeter 100 cm is to be rolled to form a cylindrical tube. Find the dimensions of the paper that will produce a tube with maximum volume