1. The problem statement, all variables and given/known data Find the mass M of a sphere of radius a, if its mass density is proportional to the distance from the center of the sphere. 2. Relevant equations Triple integrals using spherical coordinates 3. The attempt at a solution The only place where I am stuck is if the density is KpcosΦ or just Kp. So is it integrating KpcosΦp2sinΦ or Kp3sinΦ?