AHSME 1951 Problem 38

A rise of $600$ feet is required to get a railroad line over a mountain. The grade can be kept down by lengthening the track and curving it around the mountain peak. The additional length of track required to reduce the grade from $3\%$ to $2\%$ is approximately: $\textbf{(A)}\ 10000\text{ ft.} \textbf{(B)}\ 20000\text{ ft.} \textbf{(C)}\ 30000\text{ ft.} \textbf{(D)}\ 12000\text{ ft.} \textbf{(E)}\ \text{none of these}$