1. The problem statement, all variables and given/known data I've had lectures on the thoery of this topic, but I've not been given any examples and I'm struggling with how to apply the theory to this homework question: A particle is described by the normalised wave function Si(x,y,z)=Ae^-h(x^2+y^2+z^2) where A and h are real positive constants. Determine the probability of finding the particle at a distance between r and r+dr from the origin. 2. Relevant equations p=integral (mod[Si(x,y,z)])^2 dxdydz 3. The attempt at a solution I thought that the wave function was supposed to involve complex numbers, but there's no i in the wave function? I thought i needed the conjugate of the wave function to find mod[Si(x,y,z)]? I think once i find (mod[Si(x,y,z)])^2 i then need to integrate it over the volume of a spherical shell with radius r and thickness dr, so r^2=x^2+y^2+z^2 but I'm confused about how to compute this integral. Do i need to parametrise the variables? I'm obviously not asking for someone to give me the solution, but I'm having a hard time figuring out where to start with this problem, so any help would be greatly appreciated.