1. The problem statement, all variables and given/known data Air is being pumped into a spherical balloon. Suppose we know the surface area of the balloon increases at a rate of 20cm^2/s when its radius is 4cm. What is the rate its volume is changing at that instant? 2. Relevant equations 3. The attempt at a solution I went.... dv/dt = 4∏ (4)^2 * 20/1 = 1280∏ I know its wrong. Anyone help me out? What am i doing wrong?