4. (6 pts) A city is looking at building a bridge over a set of railroad tracks. It is estimated cost is $250,000. The benefits to the city's population through reduced congestion and less wear and tear on their automobiles is estimated at $30,000/year. Maintenance cost each year is estimated to be $10,000. Businesses in the vicinity of the new bridge are estimated to lose $7,000 in profits every year due to reduced customer access. The bridge is expected to have a 50-year life and cost $75,000 to tear down then (negative salvage cost). If the interest rate is 5%, should the city construct the bridge using Conventional B/C ratio Modified B/C ratio