The 8 overhead doors at the loading dock of a warehouse must be replaced now. There are two types of replacement doors available.

• Plastic doors will cost $1,000 each, have a useful life of three years, and cost $50 per door to be disposed of at the end of the useful life.
• Aluminum doors will cost $2,800 each, last for nine years, and have a salvage value of $200 per door at the end of the useful life. The use of aluminum on all 8 doors will also save the warehouse a total of $800 per year in heating costs.

Assuming that all 8 doors will be replaced with the same type of door and using MARR = 12%, use present worth analysis to determine which type of doorplastic or aluminumshould be selected. Be sure show all your work.