I have updated the graph in the attached Maple document based on Doug Meade's comment below.
Car Talk, a humorous phone-in program in which Tom and Ray Magliozzi (Click and Clack, the Tappet Brothers) diagnose and offer solutions for mysterious auto-related maladies, is carried by National Public Radio in the USA. One of the program's segments is a weekly Puzzler, a logic (or other) mental puzzle tossed out as a challenge to the audience. The Puzzler for September 22, 2012, centered on the paradoxical result that an average over a complete set can differ greatly from averages computed over subsets. The attached worksheet details the full Puzzler, and some calculations that it provoked. It contains 2D math, so rather than display it here, it's left for download.