Volume Flow Rate

Problem
Gas is escaping from a spherical balloon at a constant rate of 2 ft³/min. How fast, in ft²/min, is the outer surface area of the balloon shrinking when the radius is 12 ft?

Problem
A conveyor is dispersing sands which forms into a conical pile whose height is approximately 4/3 of its base radius. Determine how fast the volume of the conical sand is changing when the radius of the base is 3 feet, if the rate of change of the radius is 3 inches per minute.