1. The problem statement, all variables and given/known data A point source of sound emits energy equally in all directions at a constant rate and a person 8m from the source listens. After a while, the intensity of the source is halved. If the person wishes the sound to be seem as loud as before, how far should he be now? 2. Relevant equations intensity is inversely proportional to radius(distance from the source) 3. The attempt at a solution I = (K)/(r^2) I*(r^2)=K So i presumed that since K has to be constant, and I has been halved. The radius would be (2)^(1/2). So why isn't the answer (2^(1/2))r ? I can understand that the answer is not correct because it is not possible for the intensity to be the same when the radius has increased. So can someone point out to me which part I went wrong? Thank you.