Selina Concise Class 8 Math Chapter 21 Surface Area Volume and Capacity Exercise 21C Solution

Selina Concise Class 8 Math Chapter 21 Surface Area Volume and Capacity Exercise 21C Solution

Concise Mathematics – Class 8 Selina Exercise 21C Solution by experts | 21C Selina Concise Solution Class 8 | Class 8 Selina Concise Ex 21C Page 241 Solution | RK Bansal Class 8 ICSE Book Solution Online.

(1) The edges of three solid cubes are 6 cm, 8 cm and 10 cm. These cubes are melted and recasted into a single cube. Find the edge of the resulting cube.

(2) Three solid cubes of edges 6 cm, 10 cm and x cm are melted to form a single cube of edge 12 cm. find the value of x.

(3) The length of the diagonal of a cube is 8√3 cm. Find its:

(i) edge (ii) total surface area (iii) volume

(4) A cube of edge 6 cm and a cuboid with dimensions 4 cm x X cm x 15 cm are equal in volume. Find:

(i) the value of x.

(ii) total surface area of the cuboid.

(iii) total surface area of the cube.

(iv) which of these two has greater surface and by how much?

Solution:

(5) The capacity of a rectangular tank is 5.2 meter cube and the area of its base is 2.6 x 104 cm2, find its height (depth).

(6) The height of a rectangular solid is 5 times its width adn its length is 8 times its height. If the volume of the wall is 102.4 cm3, find its length.

(7) The ratio between the lengths of the edges of two cubes are in the ration 3:2. Find the ratio between their:

(i) total surface area

(ii) volume

Solution:

(8) The length, breadth and height of a cuboid (rectangular solid) are 4:3:2

(i) If its surface area is 2548 centimeter square, find its volume.

(ii) If its volume is 3000 meter cube, find its surface area.

Solution:


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