A cylindrical wooden barrel with a bottom diameter of 20 cm contains water. An iron cone with a bottom diameter of 12 cm and a height of 30 cm is placed in the water. When the cone is taken out, how many centimeters does the water level in the barrel drop?
一个底面直径是20厘米的圆柱形木桶里装有水，水中放着一个底面直径为12厘米，高是30厘米的铁质圆锥体，当取出圆锥后，桶中水面降低了多少厘米？
<gadget id="calculator">12 / 2</gadget>
<output>6</output>

<gadget id="calculator">6 ** 2</gadget>
<output>36</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">3.14 * 36 * 30 * (1/3)</gadget>
<output>1_130.4</output>

<gadget id="calculator">20 / 2</gadget>
<output>10</output>

<gadget id="calculator">10 ** 2</gadget>
<output>100</output>

<gadget id="calculator">3.14 * 100</gadget>
<output>314</output>

<gadget id="calculator">1_130.4 / 314</gadget>
<output>3.6</output>

<result>3.6</result>