9. (1 point) A cup of coffee at 181 degrees is poured into Note: Express your answer as a positive speed. a mug and left in a room at 72 degrees. After 7 minutes, the 12. (1 point) A spherical snowball is melting so that its di- coffee is 144 degrees. ameter is decreasing at rate of 0.2 cm/min. At what rate is the volume of the snowball changing when the diameter is 12 cm. Assuming that Newton's Law of Cooling applies: Answer: cm / min (a) Determine the temperature of the coffee after 17 minutes. [Hint: Volume of a sphere with radius r is V = jar.] 13. (1 point) Gravel is being dumped from a conveyor belt T(17) degrees at a rate of 30 m /min. It forms a pile in the shape of a right circular cone whose diameter and height are always equal. How fast is the height of the pile increasing when the pile is 24 m (b) After how many minutes will the coffee be 100 degrees? high? minutes Answer: m/ min 10. (1 point) Suppose xy = 4. If " =3, find - dx [Hint: The volume of a cone with height h and radius r is when x = 3. dt given by V = {ar h.] Answer: 14. (1 point) A street light is at the top of a 13 ft tall pole. A 6ft tall woman walks away from the pole (along a straight path) 11. (1 point) A person is pulling a boat into dock with a rope. at a speed of 6 ft/sec. If the person is pulling from a height of I'm above the boat and the rope is being pulled at a rate of 1 m/s, how fast is the boat How fast is the tip of her shadow moving when she is 50 ft approaching the dock when it is 7 m from the dock? from the base of the pole? Answer: m/s Answer: . ft/ sec