2013-II-12

$\begin{array}{cl}
= & 36\text{ cm}^2 : 900\text{ m}^2 \\
= & 36\text{ cm}^2 : 9~000~000\text{ cm}^2 \\
= & 1 \text{ cm}^2 : 250~000 \text{ cm}^2 \\
\end{array}$

$\therefore$ 地圖上的長度 $:$ 實際長度

$\begin{array}{cl}
= & 1 \text{ cm} : 500 \text{ cm} \\
= & 1: 500
\end{array}$

$\therefore$ 該地圖的比例尺為 $1:500$.