An automobile manufacturer is considering mechanical design changes in one of its top-selling cars to reduce the weight of the car by at least 400 pounds to improve its fuel efficiency. Design engineers have identified 10 changes that could be made in the car to make it lighter. The weight saved by each design change and the estimated costs of implementing each change are summarized in the table:
Design Changes 1 2 3 4 5 6 7 8 9 10
Weight Saved (lbs) 50 75 25 150 60 95 200 40 80 30
Cost (in $1000) 150 350 50 450 90 35 650 75 110 30 

Changes 4 and 7 represent alternate ways of modifying the engine block and therefore only one of these options can be selected. The company wants to determine which changes to make in order to reduce te total weight of the car by at least 400 pounds in the least costly manner.

1) Formulate an ILP model for this problem.
2) Create a spreadsheet model for this problem