1. Julia must choose between two different designs for a safety enclosure, which will be in use indefinitely. Model A has a life of three years, a first cost of $9800, and maintenance of $1100 per year. Model B will last four years, has a first cost of $10,800 and has maintenance of $900 per year. The salvage value can be estimated for Model A using a depreciation rate of 45% and declining-balance depreciation, while a salvage value for Model B can be estimated using straight-line depreciations and the knowledge that after one year its salvage value will be $8,100. Interest is at 15%. Using a present worth analysis, which design is better?