I am still grading your tests. There were several good answers on these tests, some which caused me to rethink the problem myself. Posted is one set of solutions. I am grading the tests one problem at a time. The solution to #4 is difficult, and I will be grading this problem more leniently. I wanted to give those who had thought the geometry through a little more to have the chance to show me what they could come up with.
That said, we will cover oligopoly this week, and a bit of review on monopoly, so be sure to have read Ch. 8 and the story of Rockefeller, which is part of the book, Myth of the Robber Barons by Burton Fulsom. You can read a short speech by this author in which he mentions the ideas in this book by clicking here.