Contents

NCERT Solutions for Class 9 Maths Chapter 13 Surface Areas and Volumes Ex 13.3 are part of NCERT Solutions for Class 9 Maths. Here we have given NCERT Solutions for Class 9 Maths Chapter 13 Surface Areas and Volumes Ex 13.3.

- Surface Areas and Volumes Class 9 Ex 13.1
- Surface Areas and Volumes Class 9 Ex 13.2
- Surface Areas and Volumes Class 9 Ex 13.3
- Surface Areas and Volumes Class 9 Ex 13.4
- Surface Areas and Volumes Class 9 Ex 13.5
- Surface Areas and Volumes Class 9 Ex 13.6
- Surface Areas and Volumes Class 9 Ex 13.7
- Surface Areas and Volumes Class 9 Ex 13.8
- Surface Areas and Volumes Class 9 Ex 13.9

Board |
CBSE |

Textbook |
NCERT |

Class |
Class 9 |

Subject |
Maths |

Chapter |
Chapter 13 |

Chapter Name |
Surface Areas and Volumes |

Exercise |
Ex 13.3 |

Number of Questions Solved |
8 |

Category |
NCERT Solutions |

## NCERT Solutions for Class 9 Maths Chapter 13 Surface Areas and Volumes Ex 13.3

### Chapter 13 Surface Areas and Volumes Ex 13.3

**Assume π = unless stated otherwise.
**Question 1.

Diameter of the base of a cone is 10.5 cm and its slant height is 10 cm. Find its curved surface area.

Solution.

We have, diameter = 10.5 cm

∴ Radius (r) = = 5.25 cm and slant height (l) = 10 cm

Now, curved surface area of the cone =

**π**rl = x 5.25 x 10 = 165 cm

^{2}

Question 2.

Find the total surface area of a cone, if its slant height is 21 m and diameter of its base is 24 m.

Solution.

We have, slant height l = 21m

and diameter = 24 m

Question 3.

Curved surface area of a cone is 308 cm^{2} and its slant height is 14 cm. Find

(i) radius of the base and

(ii) total surface area of the cone.

Solution.

We have, slant height, l = 14 cm

Curved surface area of a cone =308 cm^{2}

Question 4.

A conical tent is 10 m high and the radius of its base is 24 m. Find

(i) slant height of the tent.

(ii) cost of the canvas required to make the tent, if the cost of 1 m^{2 }canvas is Rs.70.

Solution.

Question 5.

What length of tarpaulin 3 m wide will be required to make conical tent of height 8 m and base radius 6 m? Assume that the extra length of material that will he required for stitching margins and wastage in cutting is approximately 20 cm. (use π= 3.14)

Solution.

Let r, h and l be the radius, height and slant height of the tent, respectively.

Question 6.

The slant height and base diameter of a conical tomb are 25 m and 14 m, respectively. Find the cost of white-washing its curved surface at the rate of Rs. 210 per 100 m^{2}.

Solution.

We have, slant height (l) = 25 m and diameter = 14 m .

Question 7.

A joker’s cap is in the form of a right circular cone of base radius 7 cm and height 24 cm. Find the area of the sheet required to make 10 such caps.

Solution.

Question 8.

A bus stop is barricaded from the remaining part of the road, by using 50 hollow cones made of recycled cardboard. Each cone has a base diameter of 40 cm and height 1 m. If the outer side of each of the cones is to be painted and the cost of painting is ? 12 per m^{2}, what will be the cost of painting all these cones?

(Use π = 3.14 and take = 1.02)

Solution.

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