1. **State the problem:** We have a cuboid container with dimensions 10 cm (height), 5 cm (width), and 4 cm (depth). The volume of water inside is 120 ml, which equals 120 cm³. 2. **Formula used:** The volume $V$ of a cuboid is given by: $$V = \text{length} \times \text{width} \times \text{height}$$ 3. **Identify known values:** - Volume of water $V = 120$ cm³ - Width $w = 5$ cm - Depth $d = 4$ cm - Height of water $h = ?$ (this is what we want to find) 4. **Apply the formula to find the water depth:** Since the water fills the base, the volume of water is: $$120 = 5 \times 4 \times h$$ 5. **Solve for $h$:** $$120 = 20h$$ $$h = \frac{120}{20} = 6$$ 6. **Interpretation:** The depth of the water in the container is 6 cm. **Final answer:** The water depth is $6$ cm.