If the areas of the three adjacent faces of a cuboidal box are 120 cm$^2$, 72 cm$^2$ and 60 cm$^2$ respectively, then find the volume of the box.
Aptitude
Volume and Surface Area
Difficulty: Medium
Choose an option
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A720 cm$^3$
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B864 cm$^3$
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C7200 cm$^3$
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D(72)$^2$ cm$^3$
Answer
Correct Answer: 720 cm$^3$
Explanation
### Concept & Volume from Adjacent Faces
As derived from the geometric properties of a cuboid, if $x, y$, and $z$ are the areas of three adjacent faces, the volume $V$ is the square root of their product.
$$ V = \sqrt{x \times y \times z} $$
### Step-by-Step Solution
1. **Given:** $x = 120$, $y = 72$, $z = 60$.
2. **Apply Formula:**
$$ V = \sqrt{120 \times 72 \times 60} $$
3. **Simplify the Calculation:** Instead of multiplying everything out, factorize to find perfect squares.
$$ 120 \times 60 = 7200 $$
$$ V = \sqrt{7200 \times 72} $$
$$ V = \sqrt{100 \times 72 \times 72} $$
$$ V = 10 \times 72 = 720 \text{ cm}^3 $$
### Exam Strategy & Shortcut
Never multiply large numbers into a massive single integer when taking a square root. Group them efficiently. Spotting $120 \times 60 = 72 \times 100$ immediately pairs with the other $72$ to make extraction trivial.
### Common Pitfall
Getting lost in multiplying $120 \times 72 \times 60 = 518400$ and then struggling to calculate the square root of a large number without a calculator.
### Final Answer
Therefore, the correct answer is **720 cm$^3$**.