A large cube is formed from the material obtained by melting three smaller cubes of 3, 4 and 5 cm side. What is the ratio of the total surface areas of the smaller cubes and the large cube?

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A large cube is formed from the material obtained by melting three smaller cubes of 3, 4 and 5 cm side. What is the ratio of the total surface areas of the smaller cubes and the large cube?

[A].	2 : 1
[B].	3 : 2
[C].	25 : 18
[D].	27 : 20

Answer: Option C

Explanation:

Volume of the large cube = (3³ + 4³ + 5³) = 216 cm³.

Let the edge of the large cube be a.

So, a³ = 216 a = 6 cm.

Required ratio =		6 x (3² + 4² + 5²)		=	50	= 25 : 18.
		6 x 6²			36

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