A cylindrical bucket is filled with some water. After putting a conical iron block with a bottom radius of 2 decimeters and a height of 1.5 decimeters, the water level rises by 0.5 decimeters. Find the bottom area of the bucket.
一个圆柱形水桶，桶里盛了一些水，放入一个底面半径2分米、高1.5分米的圆锥形铁块后，水面升高了0.5分米，求水桶的底面积．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">1.5 / 0.5</gadget>
<output>3</output>

<gadget id="calculator">(1/3) * 3.14 * 4 * 3</gadget>
<output>12.56</output>

<result>12.56</result>