A cuboid of dimensions 9 cm × 8 cm × 6 cm has twice the volume of a cube. Find the total surface area (in cm^2) of the cube.
Aptitude
Volume and Surface Area
Difficulty: Easy
Choose an option
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A216 sq cm
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B218 sq cm
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C219 sq cm
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D213 sq cm
Answer
Correct Answer: 216 sq cm
Explanation
Introduction / Context:Relate the cuboid’s volume to twice the cube’s volume, then solve for the cube’s edge and compute its total surface area (TSA = 6a^2).
Given Data / Assumptions:
- Cuboid: 9 × 8 × 6 cm ⇒ V_cuboid = 432 cm^3.
- V_cuboid = 2 × V_cube.
Concept / Approach:Find V_cube = 432/2 = 216 cm^3. Then a^3 = 216 ⇒ a = 6 cm. Compute TSA = 6a^2.
Step-by-Step Solution:
V_cube = 216 cm^3a = 216^(1/3) = 6 cmTSA = 6 * a^2 = 6 * 36 = 216 cm^2Verification / Alternative check:Check: cube volume 6^3 = 216; twice equals 432 (the cuboid’s volume).
Why Other Options Are Wrong:They are close numerically but not the exact TSA from a = 6 cm.
Common Pitfalls:Computing lateral area instead of total; arithmetic slips in squaring or cube root.
Final Answer:216 sq cm