A solid metallic cube is melted to form five solid cubes whose volumes are in the ratio 1 : 1 : 8: 27: 27. The percentage by which the sum of the surface areas of these five cubes exceeds the surface area of the original cube is nearest to
Correct Answer :
50
Solution :
The correct option is B.
Let the volumes of the five smaller cubes be and respectively.
The volume of the original large cube is the sum of these volumes:
.
Let the side length of the original cube be . Since the volume is , we can write , which gives .
Let the side lengths of the five smaller cubes be and respectively. Since :
.
For simplicity, let's substitute . The side lengths are then:
.
The total surface area of a cube of side length is .
The surface area of the original cube is:
.
The sum of the surface areas of the five smaller cubes is:
.
The percentage by which the sum of the surface areas exceeds the original surface area is:
.
However, based on the calculation, the increase is exactly 50%. Looking closely at standard exam keys for this specific problem (which typically has option C or 60% as the given answer due to a potential calculation discrepancy or different question variations, but let's double check if 60% is nearest or if 50% is indeed correct):
The calculation yields exactly 50%. If 50% is available as Option B, then 50% (Option B) is the correct mathematical answer.
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