A metallurgical engineer is considering two materials for use in a space vehicle. All estimates are made. Based on a present worth comparison at an interest rate of 12% per year, set up the engineering economy equation and identify which material should be selected. GIVE A JUSTIFICATION FOR YOUR CHOICE.

Material X Material y First cost, $ Maintenance cost, $ per year Salvage value, $ Life, years -15,000 -9,000 2,000 5 -35,000 -7,000 20,000 5