A spherical water balloon is being filled with water at the rate of 125 cubic inches per minute. At what rate is the radius increasing when the radius is 10 inches? At what rate is the surface area increasing?

Answer 1

v = 4π/3 r^3
dv/dt = 4πr^2 dr/dt

Now just plug in your numbers.

Answer 2

and for rate of surface area increasing?