1. **Problem Statement:** Find the volume of wood in a cuboid pen stand with four conical depressions. 2. **Given:** - Cuboid dimensions: length $=15$ cm, width $=10$ cm, height $=3.5$ cm - Each conical depression: radius $r=0.5$ cm, depth (height) $h=1.4$ cm - Number of conical depressions: 4 3. **Formulae:** - Volume of cuboid: $$V_{cuboid} = l \times w \times h$$ - Volume of cone: $$V_{cone} = \frac{1}{3} \pi r^2 h$$ 4. **Calculate volume of cuboid:** $$V_{cuboid} = 15 \times 10 \times 3.5 = 525 \text{ cm}^3$$ 5. **Calculate volume of one conical depression:** $$V_{cone} = \frac{1}{3} \times \pi \times (0.5)^2 \times 1.4 = \frac{1}{3} \times 3.14 \times 0.25 \times 1.4$$ $$= \frac{1}{3} \times 3.14 \times 0.35 = 0.3663 \text{ cm}^3$$ 6. **Calculate total volume of four conical depressions:** $$4 \times 0.3663 = 1.4652 \text{ cm}^3$$ 7. **Calculate volume of wood in the pen stand:** $$V_{wood} = V_{cuboid} - V_{cones} = 525 - 1.4652 = 523.5348 \text{ cm}^3$$ **Final answer:** The volume of wood in the entire stand is approximately **523.53 cm³**.