There are two cylindrical containers A and B. Initially, container A contains 4 liters of water, and container B is empty. Now pour water into the two containers at a rate of 0.4 liters per minute. After 4 minutes, the water levels in the two containers are equal. Assuming that the radius of the bottom of container B is 5 decimeters, what is the area of the bottom of container A in square decimeters? (container thickness is ignored)
有甲、乙两个圆柱形容器，最初在甲容器里装有4升水，乙容器是空的．现在往两个容器里以每分0.4升的速度注入水，4分后两个容器里的水面高度相等，假设乙容器的底面半径为5分米，甲容器底面积是多少平方分米？(容器厚度忽略不计)
<gadget id="calculator">3.14 * 87.5</gadget>
<output>274.75</output>

<result>274.75</result>