Page 183 - Maths Skills - 8

Mensuration 181

2. The ratio of the length, breadth and height of a cuboid is 5 : 3 : 2. If its volume is 3750 cm , find the
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length, breadth and height of the cuboid.
3. The bottom of the tank of a water cooler is rectangular in shape. It is 90 cm × 60 cm. How high it must
be made, so that it can hold 162 litres of water?
4. A pit measuring 8 m by 5 m by 3 m was dug. The earth removed is evenly spread on a platform of length
12 m and breadth 4 m. Calculate the rise in level of the earth on the platform.
5. A rectangular water tank is 12 m long and 8 m wide. If it contains a maximum of 480000 l of water, what
is its depth?

6. Two cubes each of side 5 cm are placed together. Find the volume of cuboid, thus obtained.
7. A box is 54 cm × 45 cm × 300 cm. How many soaps can be fitted in it if each measures 9 cm × 5 cm × 3
cm?
8. A water reservoir is 2 m long, 1.5 m wide and 1.5 m high. How many litres of water can it hold?
9. A cuboid is made of metal. It is 27 cm × 18 cm × 12 cm. It is melted and recast into small cubes with an
edge 3 cm in length. How many cubes are made?
10. The cover box of a laptop measures 45 cm by 40 cm by 30 cm. If a cardboard packet contains a maximum
of 15 such cover boxes of laptops, find the volume of the cardboard packet.
11. A rectangular block of ice measures 42 cm × 25 cm × 18 cm. Calculate its weight in kilograms if 1 cm
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of ice weighs 0.9 grams.
12. Find the volume of the cuboids whose

(i) l = 15 cm, b = 7 cm and h = 6 cm (ii) l = 2.3 m, b = 30 cm and h = 7 cm
13. Find the number of cubes of 4 cm long that can be made from a cuboid of dimensions 24 cm × 20 cm ×
12 cm.
14. How many 4 cm long cubes can be cut from a cube whose edges are 20 cm in length?

15. The volume of a cube is 64 cm . Find the length of its edge.
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16. The rainfall on a certain day was 4 cm. How many litres of water fell on 4 hectares of field on that day?
17. Find the volume of a cuboid whose length is double its breadth and height is half of the breadth.
18. What will be the labour charges for digging a cuboidal pit 6 m long, 5 m broad and 4 m deep at the rate
of 15 per 1000 dm ?
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RIGHT CIRCULAR CYLINDER

A cylinder is defined as a solid having two uniform cross-sections and a curved
lateral surface. A circular pipe, a circular pencil, a road roller, a circular pillar are
some of the examples of cylinder.

The Fig. [(i) and (ii)], given alongside are cylinders.
Some basic terms related to cylinder are as follows: (i) (ii)
(i) Bases: The circular ends on which the cylinder rests are called its base. There are two circular bases in a
cylinder.
(ii) Radius: The radius of the circular bases is the radius of the cylinder.

(iii) Axis: A line segment joining the centre of the two bases is called the axis of the cylinder. OO′ is the axis
of the cylinder.

(iv) Height: The length between the two circular ends or the perpendicular distance between the two ends is
called the height of the cylinder.