水体积=圆锥体积：V = π × r^2 × h / 3=π × 3^2 × 8 / 3 = 24 π
圆柱体积公式：V = π × R^2 × H = π × 4 × H
由于水的体积V不变,所以：
π × 4 × H = 24 π
H = 24 / 4 = 6 (分米)