4. A spherical balloon is being inflated so that its diameter is increasing at a rate of 2 cm/min. How quickly is the volume of the balloon increasing when the diameter is 20 cm? 5. The radius of a cylinder is increasing at a rate of 1 meter per hour, and the height of the cylinder is decreasing at a rate of 2 meters per hour. At a certain instant, the base radius is 4 meters and the height is 6 meters. What is the rate of change of the volume of the cylinder at the instant