An air sampling station can be powered by a solar cell or an electric line. At an interest rate of 10% per year, determine [8] Electric line Solar cell First cost, $ 20,000 30,000 Annual O&M cost, $/year 4,000 1,000 Life, years 5 5 1. Which alternative should be selected on the basis of an annual worth analysis? [5] 2. What must be the first cost of the other alternative to be equally attractive economically? [3]