A cylindrical glass vessel with a bottom radius of 8 cm is filled with water. A conical plumb bob with a bottom radius of 4 cm is immersed in the water. When the plumb bob is taken out of the water, the water level drops by 2 cm. What is the volume of this plumb bob?
一个底面半径是8cm的圆柱形玻璃器皿装满了水，水中浸着一个底面半径是4cm的圆锥形铅锤，当铅锤从水中取出后，水面下降了2cm．这个铅锤的体积是多少？
<gadget id="calculator">8 ** 2</gadget>
<output>64</output>

<gadget id="calculator">3.14 * 64 * 2</gadget>
<output>401.92</output>

<result>401.92</result>