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5. If the side of a cubical box is 18 cm, then find its lateral surface and total surface area.

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6. Find the side of a cube whose total surface area is 150 cm .
7. A road roller has to take 500 complete revolutions to level a road. Find the area of the road if the
radius of the road roller is 21 cm, and the length is 100 cm.
8. By how many times will the total surface area of a cube increase if each of its sides is doubled?

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9. The dimensions of a cuboid are in the ratio 5 : 3 : 1 and its total surface area is 414 m , find the
dimensions of the cuboid.
10. A box that is in the form of a cuboid has external dimensions of 120 cm × 40 cm × 60 cm. Except for
the front and top faces, all the faces are to be covered with brown paper. Find the area of the paper
needed.
11. Find the curved surface area and total surface area of a right circular cylinder whose base has a
radius of 7 cm and height of 8 cm.
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12. The total surface area of a cylinder is 484 cm . Find the height of a cylinder given that its radius is
7 cm.

13. A closed cylindrical tank of radius 14 m and height 6 m is made from a sheet of aluminium. Find
the area of the required sheet?
14. 12 cylindrical drums, each having a radius of 28 cm and height of 50 cm, are to be painted on their
curved side. Find the total cost of painting all drums at the rate of `150 per m .
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15. Raman wants to paint the walls and ceiling of his room whose dimensions are 15 m, 10 m and 7 m
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respectively. How many cans of paint will he need if one can covers 100 m of the area?
Volume of Cuboid, Cube and Cylinder

The volume of a three-dimensional object is defined as the amount of space occupied by that
object. Now, tell which will have more volume — a water tank or a bucket. It is obvious that a water
tank which can contain more quantity of water will have more volume than a bucket. Similarly,
the volume of a die will be less than the volume of a chalk box, and so on.

Let us learn how to measure the volume of a cuboid, cube, or cylinder using formulae.
We use square units to find the area of a region. However, to find the volume, we will use cubic

units.
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Just like the area is measured in square units namely cm , dm , m , etc., we can measure the
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3
3
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volume in cubic units, namely, cm , dm , m .
1 cubic cm = 1 cm × 1 cm × 1 cm = 1 cm 3
3
1 cubic dm = 1 dm = 1 dm × 1 dm × 1 dm
= 10 cm × 10 cm × 10 cm = 1000 cm 3
3
1 cubic mm = 1 mm = 1 mm × 1 mm × 1 mm
= 0.1 cm × 0.1 cm × 0.1 cm = 0.001 cm 3

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1 cubic m = 1 m = 1 m × 1 m × 1 m
3
= 100 cm × 100 cm × 100 cm = 1000000 cm .

249 Mensuration