p-adic wrote:What is an Econ Ph.D. doing writing these solutions?
There could be many reasons for this: (1) she could have an undergraduate degree in mathematics; (2) she could be a math tutor, etc. Moreover, economists often use a lot of math in their research, so there is no surprise here. Most importantly, she is doing us test takers a big favor because it takes quite a lot of hard work and dedication just to do the typesetting and the graphics. I welcome her answers as they are well-written, detailed and carefully presented, and would encourage her to post more solutions to her blog.