# NCERT Solutions for Class 9 Maths Chapter 13 Exercise 13.7 & 13.8

Free Download NCERT Solutions for Class 9 Maths Chapter 13 Exercise 13.7 & 13.8 surface areas and volumes in English Medium and Hindi Medium free to use online. NCERT Solutions for all subjects and the solutions of other exercises like Exercise 13.1 & 13.2 or Exercise 13.3 & 13.4 or Exercise 13.5 & 13.6 or Exercise 13.9 are also given to use online.

## NCERT Solutions for Class 9 Maths Chapter 13 Exercise 13.7 & 13.8

If you need solutions in Hindi, Click for Hindi Medium solutions of 10 Maths Exercise 13.7 & 13.8          Exercise 13.1 & 13.2

Exercise 13.3 & 13.4

Exercise 13.5 & 13.6

Exercise 13.9

9 Maths Solutions – Main Page

### 9 Maths Chapter 13 Exercise 13.7 & 13.8 in Hindi        Exercise 13.1 & 13.2

Exercise 13.3 & 13.4

Exercise 13.5 & 13.6

Exercise 13.9

9 Maths Solutions – Main Page

To get the solutions in English, Click for English Medium solutions.

##### 9 Maths Chapter 13 – Surface Areas and Volumes
###### Extra Questions with Answers for Exams
1. A wall of length 10 m was to be built across an open ground. The height of the wall is 4m and thickness of the wall is 24 cm. If this wall is to be built up with bricks whose dimensions are 24 cm x 10 cm x 8 cm, how many bricks would be required? [Answer: 5000]
2. 1.1 cm³ of gold is drawn into a wire of 0.1 mm in diameter. Find the length of the wire in metre. [Answer: 140 m]
3. A hemispherical bowl of internal diameter 36 cm contain a liquid. This liquid is to be filled in cylindrical bottles of radius 3 cm and height 6 cm. How many bottles are required to empty the bowl? [Answer: 1672]
4. Find the lateral curved surface area of a cylindrical petrol storage tank that is 4.2 m in diameter and 4.5 m high. How much steel was actually used if 1/12 of steel actually used was wasted in making the closed tank. [Answer: 59.4 m², 95.04 m²]
5. Water in a canal, 30 dm wide and 12 dm deep is flowing with a speed of 20 km per hour. How much area will it irrigate in 30 min if 9 cm of standing water is desired? (10 dm = 1 m) [Answer: 400000 m²]
6. The radius of a sphere is 10 cm. If the radius is increased by 1 cm. then prove that volume of the sphere is increased by 33.1%.
7. The diameter of a hemisphere is decreased by 30%. What will be the percentage change in its total surface area? [Answer: 51%]
8. A sphere and a cube have the same surface area. Find the ratio of their volumes. [Answer: √6:√5]
9. The volume of a sphere is 4851 cm³. How much should its radius be reduced so that its volume becomes 4312/3 cm³? [Answer: 3.5 cm]
10. A cuboidal tank can store 5040 litres of water. The external dimensions of the tank are 2.2 m x 1.7 m x 1.7 m. If the walls of the tank are 5 cm thick, then what is the thickness of the bottom of the tank? [Answer: 10 cm]
11. A metallic sheet is of the rectangular shape with dimensions 48 cm x 36 cm. From each one of its corners, a square of 8 cm is cut off. An open box is made of the remaining sheet. Find the volume of the box. [Answer: 5120 cm³]