$$\begin{gathered} \mathrm{Chiều} \mathrm{dài} \mathrm{mảnh} \mathrm{đất} \mathrm{trên} \mathrm{thực} \mathrm{tế} \mathrm{là}: \\ 5\times 1000=5000 \left(\mathrm{cm}\right) \\ \mathrm{Chiều} \mathrm{rộng} \mathrm{mảnh} \mathrm{đất} \mathrm{trên} \mathrm{thực} \mathrm{tế} \mathrm{là}: \\ 3\times 1000=3000 \left(\mathrm{cm}\right) \\ \mathrm{Diện} \mathrm{tích} \mathrm{mảnh} \mathrm{đất} \mathrm{trên} \mathrm{thực} \mathrm{tế} \mathrm{là}: \\ 5000\times 3000=15000000 (\mathrm{cm}²) \\ 15000000 \mathrm{cm}² = 1500 \mathrm{m}² \\ \mathrm{Đáp} \mathrm{số}: 1500 \mathrm{m}² \end{gathered}$$