A trapezoidal wheat field has an upper base of 420 meters, a lower base of 480 meters, and a height of 200 meters. A total of 36,000 kg of wheat was harvested from this field. How many kilograms of wheat are harvested on average per hectare?
一块梯形麦地，上底是420米，下底是480米，高是200米．这块地共收小麦36000千克．平均每公顷收小麦多少千克？
<gadget id="calculator">420 + 480</gadget>
<output>900</output>

<gadget id="calculator">200 / 2 / 10_000</gadget>
<output>1/100 = around 0.01</output>

<gadget id="calculator">900 * (1/100)</gadget>
<output>9</output>

<gadget id="calculator">36_000 / 9</gadget>
<output>4_000</output>

<result>4_000</result>