First, we {{CMD_303}}introduce several variables{{CMD_304}}. Let {{MATH_305}} be the volume of the water in the container, let {{MATH_306}} be the radius of the circular surface of the water, and let {{MATH_307}} be the depth of the water in the container. The given rate is {{MATH_308}} {{MATH_309}}, and the unknown rate is {{MATH_310}}, at the moment when {{MATH_311}} cm. Now, we {{CMD_312}}draw a picture{{CMD_313}}. {{CMD_314}} {{ENV_315}} {{CMD_316}} Note, no attempt was made to draw this picture to scale, rather we want all of the relevant information to be available to the mathematician.