1. A rectangular playground is to be fenced off and divided into two parts by a fence parallel to one side of the playground. 240 feet of fencing is used. Find the dimensions of the playground that will enclose the greatest total area.
2. A spherical snowball is melting in such a manner that its radius is changing at a constant rate, decreasing from 21 cm to 10 cm in 30 minutes. At what rate, in cubic cm per minute, is the volume of the snowball changing at the instant the radius is 3 cm?