A cylindrical container with a bottom diameter of 20 cm and a height of 30 cm is filled with water. A cone with a bottom diameter of 18 cm and a height of 15 cm is placed in the water. If the cone is taken out, what will happen to the water surface?
底面直径是20厘米，高30厘米的圆柱形容器中装满水，水中放着一个底面直径18厘米，高15厘米的圆锥，拿出圆锥，水面会发生什么现象．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">18 / 2</gadget>
<output>9</output>

<gadget id="calculator">9 ** 2</gadget>
<output>81</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">15 / 314</gadget>
<output>15/314 = around 0.047771</output>

<gadget id="calculator">(1/3) * 3.14 * 81 * (15/314)</gadget>
<output>4.05</output>

<result>4.05</result>