1. The problem statement, all variables and given/known data Separate variables and integrate to find an expression for r(t), given r0 at t=0 2. Relevant equations M=ρ(4/3)πr3, thus V=(4/3)πr3 dM/dt=Cr3 where C is a constant 3. The attempt at a solution ∫dM=∫Cr3dt M+constant=?? I have no idea how to integrate r because it's a function of t but we're not given the function. I don't think that integrating the left side this way will be very helpful either. Any advice would be much appreciated!