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

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

Concise Mathematics – Class 8 Selina Exercise 21E Solution by experts | 10C Selina Concise Solution Class 8 | Class 8 Selina Concise Ex 21E Page 244 Solution | RK Bansal Class 8 ICSE Book Solution Online.

(1) A cuboid is 8 m long, 12 m broad and 3.5 m high. Find its

(i) total surface area

(ii) lateral surface area

(2) How many bricks will be required for constructing a wall which is 16 m long, 3 m high and 22.5 cm thick, if each brick measures 25 cm x 11.25 cm x 6 cm?

Solution: 

(3) The length, breadth and height of cuboid are in the ratio 6:5:3. If its total surface area is 504 cm square, find its volume.

Solution:

(4) The external dimensions of an wooden box are 65 cm, 34 cm and 25 cm. if the box is made up of wood 2 cm thick, find the capacity of the box and the volume of wood 2 cm thick, find the capacity of the box and the volume of wood used to make it.

Solution:

(5) The curved surface area and the volume of a toy, cylindrical in shape, are 132 cm square and its length.

Solution:

(6) The floor of a rectangular hall has a perimeter 250 m. If the cost of painting the four walls at the rate of Rs. 10 per meter square is Rs. 15,000, find the height of the hall.

Solution:

(7) The length of a hall is double its breadth. Its height is 3 m. The area of its four walls (including door and windows) is 108 meter square, find its volume.

(8) A solid cube of side 12 cm is cut into 8 identical cubes. What will be the side of the new cube? Also, find the ratio between the surface area of the original cube and the total surface area of all the small cubes formed.

Solution:

(9) The diameter of a garden roller is 1.4 m and it is 2 m long. Find the maximum area covered by it in 50 revolutions?

(10) In a building, there are 24 cylindrical pillars. For each pillar, radius is 28 cm and height is 4 m. Find the total cost of painting the curved surface area of the pillars at the rate Rs. 8 per meter square.

Solution:


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