If a cuboid of dimensions 32 cm × 12 cm × 9 cm is cut into two cubes of same size, what will be the ratio of the total surface area of the cuboid to the total surface area of the two cubes? 

 If a cuboid of dimensions 32 cm × 12 cm × 9 cm is cut into two cubes of same size, what will be the ratio of the total surface area of the cuboid to the total surface area of the two cubes?  Correct Answer  65 : 72 

Given:

A cuboid of dimensions 32 cm × 12 cm × 9 cm is cut into two cubes of same size.

Formula used:

Volume of a cuboid = L × B × H

Volume of a cube = (side of a cube)3

Total surface area of a cuboid = 2(L × B + B × H + H × L)

Total surface area of a cube = 6 × (side)2

Calculation:

Let side of a new cube be a.

Volume of cuboid = Volume of two same cubes

⇒ 32 × 12 × 9 = 2 × a3

⇒ 1728 = a3

⇒ 12 = a

Total surface area of a cuboid = 2(32 × 12 + 12 × 9 + 9 × 32) = 2 × 12 × 65

Total surface area of a cube = 6 × 122 = 6 × 12 × 12

Required ratio =  2 × 12 × 65 : 2 × 6 × 12 × 12 = 65 : 72

∴ The ratio of the total surface area of the cuboid to the total surface area of the two cubes is 65 : 72.

 

 

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