Question

The ratio of the length, breadth and the height of a solid is4:2:3.If the total length of all the 12 edges of this  

     cuboid is 180 m,What is the cost of painting its surface at the rate of  `5 per square metre?  

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Answer 1

The rectangular solid is a cuboid.

Let the length of the cuboid =5a, breadth =4a, and height =2a

Total surface area of a cuboid of length l, breadth b and height h =2(l×b+b×h+l×h)

Given, total surface area of the cuboid =1216cm

2

⇒2(5a×4a+4a×2a+2a×5a)=1216cm

2

⇒76a

2

=1216

⇒a=4

Hence, the length of the cuboid =5a=20 cm, breadth =4a=16 cm, height =2a=8 cm

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