Last updated at March 3, 2017 by Teachoo

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Example 2 Hameed has built a cubical water tank with lid for his house, with each outer edge 1.5 m long. He gets the outer surface of the tank excluding the base, covered with square tiles of side 25 cm (see Fig. ). Find how much he would spend for the tiles, if the cost of the tiles is Rs 360 per dozen. Number of tiles required = (๐๐ข๐๐๐๐๐ ๐๐๐๐ ๐๐๐ ๐ก๐๐๐๐ ๐ก๐ ๐๐๐ฃ๐๐)/(๐ด๐๐๐ ๐๐ ๐๐๐โ ๐ก๐๐๐) We put tiles on 5 faces One face is of form square Area of 1 face = Side2 Area of 5 faces = 5 ร Area of 1 face = 5 ร Side2 = 5 ร (1.5 m)2 = 5 ร (1.5 ร 100 cm)2 = 5 ร (150)2 cm2 Now, We find area of tile Tile is in form of square of side 25 cm Area of 1 tile = side ร side = 25 ร 25 cm2 Number of tiles required = (๐ด๐๐๐ ๐๐ 5 ๐๐๐๐๐ )/(๐ด๐๐๐ ๐๐ 1 ๐ก๐๐๐) = (5 ร (150)^2)/(25 ร 25) = (5 ร 150 ร 150)/(25 ร 25) = 180 Now, We have to find cost of tiles. Given that cost of 1 dozen tiles = Rs 360 โด Cost of 12 tiles = Rs 360 Cost of 1 tile = Rs (360 )/12 Cost of 180 tiles = Rs (360 )/12 ร 180 Cost of 180 tiles = Rs 5400 So, Hameed spends Rs 5400 on the tiles

Example 2
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Ex 13.1, 6 Important

Ex 13.1, 7 Important

Ex 13.2, 3 Important

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Ex 13.2, 9 Important

Example 6 Important

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Ex 13.4, 3 Important

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Ex 13.4, 9 Important

Ex 13.5, 6 Important

Ex 13.5, 8 Important

Ex 13.5, 9 Important

Example 14 Important

Ex 13.6, 3 Important

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Example 18 Important

Ex 13.8, 4 Important

Surface Area and Volume Formulas Important

Class 9

Important Questions for Exam - Class 9

- Chapter 1 Class 9 Number Systems
- Chapter 2 Class 9 Polynomials
- Chapter 3 Class 9 Coordinate Geometry
- Chapter 4 Class 9 Linear Equations in Two Variables
- Chapter 5 Class 9 Introduction to Euclid's Geometry
- Chapter 6 Class 9 Lines and Angles
- Chapter 7 Class 9 Triangles
- Chapter 8 Class 9 Quadrilaterals
- Chapter 9 Class 9 Areas of parallelograms and Triangles
- Chapter 10 Class 9 Circles
- Chapter 11 Class 9 Constructions
- Chapter 12 Class 9 Herons Formula
- Chapter 13 Class 9 Surface Areas and Volumes
- Chapter 14 Class 9 Statistics
- Chapter 15 Class 9 Probability

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He provides courses for Mathematics from Class 9 to 12. You can ask questions here.