1. The problem statement, all variables and given/known data The problem (4.13 (b) in Grifitths) asks to find <x^2> of the ground state of hydrogen atom. It asks to do so without new integration. Supposedly, there is some kind of symmetry and one can use the results from part (a) of the problem. Part (a) is finding <r> and <r^2> for the same state. 2. Relevant equations 3. The attempt at a solution I am failing to see the symmetry he is talking about.