1. Let's say that the benefits to the City of Dallas from Trinity Groves near downtown Dallas are measured at $300,000 a year. These benefits will
continue into the future for a long time, so that the stream of benefits can be considered a perpetuity. If the appropriate discount rate is 3%, what is the
present value of the perpetuity?
 

2. If the discount rate was lower, what would happen to the present value of the perpetuity?
 

3. Why are social discount rates lower and social time horizons longer than any rate for an individual?