Suppose a small town is considering how much effort to put into cleaning up a polluted stream. The town has a population of 10 people, each of whom values the stream cleanup based on MWTP = 5 - 0.5H, where H is the total number of worker-hours spent cleaning up the stream and MWTP is marginal willingness to pay (in dollars per worker-hour of cleanup). The cleanup costs $8 per worker-hour. What is the efficient number of worker-hours for the cleanup?