A and B are two cylindrical containers, A contains 2000ml of water, and B is empty, now pour 1600ml of water into each of the two containers, the heights of their water surfaces are equal, it is known that the radius of the bottom of A is 9 cm, find B radius of the base.
甲乙两个圆柱形容器，甲容器中有水2000毫升，乙是空的，现往两个容器里各注入水1600毫升，它们水面的高度相等，已知甲的底面半径为9厘米，求乙的底面半径．
<result>6</result>