1) Air is leaking out of a spherical balloon at the rate of 3 cubic cm/sec. When the radius is 5 cm, how fast is the surface area decreasing?
2) A cone shaped paper cup is being filled with water at the rate of 3 cubic cm/sec. The height of the cup is 10 cm and the radius of its base is 5 cm. How fast is the water level rising when the level is 4 cm?
3) A ship B is moving westward toward a fixed point A at a speed of 12km/h. At the moment when the ship is 72 km away from A, a ship C passes through A, heading due south at 10km/h. What is the rate of change in the distance between the ships two hours after ship C passed through A?