1) A spherical party balloon is being inflated with helium pumped in at a rate of 6 cubic feet per minute. How fast is the radius growing at the instant when the radius has reached 3 ft? HINT [See Example 1.] (The volume of a sphere of radius r is

V = 4/3r^3

Round your answer to two decimal places.

2) The base of a 30-foot ladder is being pulled away from a wall at a rate of 13 feet per second. How fast is the top of the ladder sliding down the wall at the instant when the base of the ladder is 18 feet from the wall? HINT [See Example 2.] ft/s