下图所示的容器由 2 个长方体和一个棱长为 6 cm 的正方体组成。小长方体的底面是一个边长为 3 cm 的正方形。大长方体的尺寸为 16 cm $\times$ 9 cm $\times$ 5 cm。容器内有 864 ml 的水，且小长方体和正方体中的水面高度相同。求水面距离容器底部的高度是多少？ 答案: ___

1. Calculate the volume of the big cuboid at the base.

Volume of big cuboid $= 16 \times 9 \times 5 = 720 \text{ cm}^3$

2. Calculate the remaining volume of water that goes into the small cuboid and the cube.

Total volume of water $= 864 \text{ ml} = 864 \text{ cm}^3$
Remaining volume $= 864 - 720 = 144 \text{ cm}^3$

3. Calculate the combined base area of the small cuboid and the cube.

Base area of small cuboid $= 3 \times 3 = 9 \text{ cm}^2$
Base area of cube $= 6 \times 6 = 36 \text{ cm}^2$
Combined base area $= 9 + 36 = 45 \text{ cm}^2$

4. Calculate the height of the water level in the small cuboid and the cube, and then the total height from the base.

Height of water in upper parts $= 144 \div 45 = 3.2 \text{ cm}$
Total height from base $= 5 + 3.2 = 8.2 \text{ cm}$