The volume of the largest sphere which can be carved out of a cube of side $6$ cm is
Aptitude
Volume and Surface Area
Difficulty: Easy
Choose an option
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A$113.14 \text{ cm}^3$
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B$166 \text{ cm}^3$
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C$179.66 \text{ cm}^3$
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D$188.52 \text{ cm}^3$
Answer
Correct Answer: $113.14 \text{ cm}^3$
Explanation
### Concept & Inscribed Sphere
The largest sphere that can be carved from a cube perfectly touches the centers of the cube's six faces. Therefore, the diameter of this largest sphere is exactly equal to the side length of the cube.
$$d_{\text{sphere}} = a_{\text{cube}}$$
Volume of a sphere $= \frac{4}{3}\pi r^3$.
### Step-by-Step Solution
* **Given:** Side of the cube $a = 6$ cm.
* Diameter of the largest possible sphere $d = 6$ cm.
* Radius of the sphere $r = \frac{6}{2} = 3$ cm.
* Volume of the sphere $= \frac{4}{3} \times \pi \times r^3$.
* Volume $= \frac{4}{3} \times \frac{22}{7} \times 3^3 = \frac{4}{3} \times \frac{22}{7} \times 27$.
* Volume $= 4 \times \frac{22}{7} \times 9 = \frac{792}{7}$.
* Convert to decimal: $792 \div 7 = 113.1428... \text{ cm}^3$.
### Exam Strategy & Shortcut
Recognize that the volume of a sphere inscribed in a cube is about $52.4\%$ of the cube's volume ($\frac{\pi}{6}$). The cube's volume is $6^3 = 216$. Roughly half of $216$ is $108$. The only option close to this estimation is $113.14$.
### Common Pitfall
Using the cube's diagonal to find the sphere's radius. The diagonal determines the *circumscribed* sphere (outside the cube), but a *carved* sphere is inscribed (inside), limited by the flat faces, not the corners.
### Final Answer
Therefore, the correct answer is **$113.14 \text{ cm}^3$**.