1991 AHSME Problem 8

Liquid X does not mix with water. Unless obstructed, it spreads out on the surface of water to form a circular film 0.1cm thick. A rectangular box measuring 6cm by 3cm by 12cm is filled with liquid X. Its contents are poured onto a large body of water. What will be the radius, in centimeters, of the resulting circular film?

\textbf{(A) } \frac{\sqrt{216}}{\pi} \qquad \textbf{(B) }\sqrt{\frac{216}{\pi}} \qquad \textbf{(C) } \sqrt{\frac{2160}{\pi}} \qquad \textbf{(D) } \frac{216}{\pi} \qquad \textbf{(E) } \frac{2160}{\pi}

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.