What is the Density of Pluto

Any chance I get to restore Pluto to its former glory, I'm going to take it.  What really threw me for a loop was the second 'tacked on' question here.  The problem being that this person has extra information, which is the article by Peale et al. in their textbook.  Using my powers of librarianship I 'hypothesized' that predictions about volcanic activity on the moons of Jupiter would probably have little to do with how tides affect volcanoes on earth, I decided to focus my research their in the hopes of offering up appropriate resources to lead the person to the right conclusion on his or her own. 

Here is the link to the question
What is the density of Pluto?