RBSE Solutions for Class 8 Maths Chapter 15 Surface Area and Volume Ex 15.2 is part of RBSE Solutions for Class 8 Maths. Here we have given Rajasthan Board RBSE Class 8 Maths Chapter 15 Surface Area and Volume Exercise 15.2.

Board |
RBSE |

Textbook |
SIERT, Rajasthan |

Class |
Class 8 |

Subject |
Maths |

Chapter |
Chapter 15 |

Chapter Name |
Surface Area and Volume |

Exercise |
Exercise 15.2 |

Number of Questions |
8 |

Category |
RBSE Solutions |

## Rajasthan Board RBSE Class 8 Maths Chapter 15 Surface Area and Volume Ex 15.2

Question 1.

Dimensions of a cuboid are 60 cm. x 54 cm. x 30 cm. How many cubes of side 6 cm. can be placed in the cuboid?

Solution:

Volume of cuboid

= 60 x 54 x 30 cm.³

= 97200 cm.³

Volume of cube of side 6 cm.

= (6)³

= 216 cm.³

∴Required(RBSESolutions.com)Number of cubes

= 450 cubes

Question 2.

How many wooden logs of side 6 cm can be cut from a 3 m long, 50 cm broad and 25 cm high wooden pile.

Solution:

Volume of wooden pole

= 300 x 50 x 251 | 1 meter = 100 cm.

= 375000 cm.³

Volume of 1 cubical(RBSESolutions.com)block = 25 x 25 x 25

= 15625 cm.³

∴Required number of cubical blocks

= 24

Question 3.

Cylinder A has diameter of 14 cm and height of 7 cm and cylinder B has diameter 7 cm and height 14 cm. Without calculation tell volume of which cylinder is more? Verify the answer by calculation.

Solution:

For cylinder A

Radius of base (r) = \(\frac { 14 }{ 2 }\) cm. = 7 cm.

Height (h) = 7 cm.

∴ Volume = πr²h

= \(\frac { 22 }{ 7 }\) . (7)² . (7)

= 1078 cm.³

For cylinder B

Radius(RBSESolutions.com)of Base (R) = \(\frac { 7 }{ 2 }\)cm.

Height (H) = 14 cm.

∴ Volume = πR²H

= \(\frac { 22 }{ 7 } .\frac { 7 }{ 2 } .\frac { 7 }{ 2 } .14\)

= 539 cm.³

Hence, volume of cylinder A is 1078 – 539 = 539 cm.³ is greater than cylinder B.

Question 4.

From a cylindrical milk tanker of radius 1.5 m and length 7 m how many polythene of one liter can be packed? (1 m³ = 1000 liter)

Solution:

For tanker

Radius (r) = 1.5 meter

Height (h) = 7 meter

∴ Volume = πr²h

= \(\frac { 22 }{ 7 }\) . (1.5) (1.5) x 7

= 49.5 m³

= 49.5 x 1000 litre

= 49500 litre

Hence, the required(RBSESolutions.com)number of polythene packs are 49500.

Question 5.

In what time a tap giving 60 litres of water per minute can fill a cylindrical tank of radius 3.5 m and depth 3 m.

Solution

For tank

Radius (r) = 3.5 meter

Depth (h) = 3 meter

∴ Volume = πr²h

= \(\frac { 22 }{ 7 }\) x 3.5 x 3.5 x 3

= 115.5 m3

= 115.5 x 1000 litre

= 115500 liter

Question 6.

Dimensions of a cuboidal ice is 50 cm x 30 cm x 20 cm. Find its weight in kilogram. If weight of 1000 cm³ ice is 900 gram.

Solution

Volume of ice plate

= 50 x 30 x 20

= 30000 cm.³

∴Weight of ice plate

= 30000 x \(\frac { 900 }{ 1000 }\)

= 27000 grame

= \(\frac { 27000 }{ 1000 }\)

= 27 kg.

Question 7.

If side of a cube is doubled then,

(i) How many times its surface area will increase?

(ii) How many(RBSESolutions.com)times its volume will increase?

Solution

(i) Let a cm. be the side of cube. Then,

Surface Area S_{1} = 6a² cm.²

New side = 2a cm.

.’. New Surface Area S_{2} = 6 (2a)²

= 24a² cm.²

We get,

S_{2} = 4 S_{1}

Hence, the surface(RBSESolutions.com)area of new cube will increase 4 times.

(ii) Volume V_{1} = a³ cm.³

Hence, the volume will increase 8 times.

Question 8.

Volume of a cylindrical tank having 7 meter diameter is 770 cubic meter. Find height of the tank.

Solution

For tank

Radius (r) = \(\frac { 7 }{ 2 }\) meter

Let height be h meter. Then,

∴ Height of the tank is 20 m.

We hope the given RBSE Solutions for Class 8 Maths Chapter 15 Surface Area and Volume Ex 15.2 will help you. If you have any query regarding Rajasthan Board RBSE Class 8 Maths Chapter 15 Surface Area and Volume Exercise 15.2, drop a comment below and we will get back to you at the earliest.

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