cylindrical water tank and a cylindrical bucket, the diameter of the bottom surface of the water tank measured from the inside is twice that of the bucket, and the depth of the water tank is twice that of the bucket, at least how many buckets of water must be filled to fill the empty water tank.
一个圆柱形水箱和一个圆柱形水桶，从里面量水箱的底面直径是水桶的2倍，水箱的深度是水桶的2倍，至少要装多少桶水才能将空水箱装满．
<result>8</result>