This is a set of solutions I starting writing in 2009 whilst studying The Road to Reality by Roger Penrose. They are written in LaTeX, with a compiled PDF available here.
Penrose wrote in the preface to Road to Reality that:
It is always the case, with Mathematics, that a little direct experience of thinking over things on your own can provide a much deeper understanding than merely reading about them. (If you need the solutions, see the website www.roadsolutions.ox.ac.uk)
Unfortunately, this site does not exist, and Penrose never published solutions. There is also an archived forum for other community solutions.