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Three Equal Cubes Are Placed Adjacently in a Row. Find the Ratio of the Total Surfaced Area of the Resulting Cuboid to that of the Sum of the Total Surface Areas of the Three Cubes - Mathematics

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Question

Three equal cubes are placed adjacently in a row. Find the ratio of the total surfaced area of the resulting cuboid to that of the sum of the total surface areas of the three cubes.

Sum

Solution

Let the side of a cube be 'a' units.

The total surface area of one cube = 6a2

The total surface area of 3 cubes  = 3 x 6a2 = 18a2

After joining 3 cubes in a row, length of Cuboid = 3a

Breadth and height of cuboid = a

The total surface area of the cuboid  = 2( 3a2 + a2 +  3a2 ) = 14a2

The ratio of total surface area of a cuboid to the total surface area of 3 cubes = `(14a^2) /(18a^2) = 7/9`

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Chapter 21: Solids [Surface Area and Volume of 3-D Solids] - Exercise 21 (A) [Page 269]

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Selina Concise Mathematics [English] Class 9 ICSE
Chapter 21 Solids [Surface Area and Volume of 3-D Solids]
Exercise 21 (A) | Q 7 | Page 269
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