Page 302 - Start Up Mathematics_8 (Non CCE)

2. The maximum length of a rod that can be kept in a cuboidal box of dimension 12 cm × 9 cm × 8 cm is:
(a) 17 cm (b) 19 cm (c) 18 cm (d) 13 cm
3. The lateral surface area of a cuboid of dimension 11 cm × 8 cm × 5 cm is:
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2
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(a) 19 cm (b) 190 cm (c) 366 cm (d) 366 cm 2
4. The sum of the areas of all six faces of a cuboid is the ___________ of the cuboid.
(a) volume (b) surface area (c) lateral surface area (d) diagonal
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5. The volume of an oil tank is 4 m . Its capacity in litres is:
(a) 40,000 (b) 4,000 (c) 400 (d) 40
6. The surface area of an open box whose length, breadth and height are l, b and h respectively is:
(a) 2(lb + bh) + hl (b) 2(bh + hl) + lb (c) 2(lb + bh + hl) (d) 2(lb + hl) + bh

solve Mentally
True or False
1. The six faces of a cube are squares of same size.
2. If the length of an edge of a cubical mug is 10 cm, then the capacity of the mug will be 1 L.
3. A hollow cylinder has a curved lateral surface with congruent circular ends.
4. When the ratio of the volumes of two cubes is 8 : 27, the ratio of their surface areas will also be 8 : 27.
5. The axis of a cylinder is always perpendicular to the circular ends.

Fill in the Blanks
1. The _________________ occupied by a solid is called its space region.
2. 1 kL = _________________ m 3

3. A solid bound by two _________________ cylinders of same height and different _________________
is called a hollow cylinder.
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4. 1 kL = _________________ dm = _________________ cm 3
5. The volume of a cuboid of dimensions 8 m × 6 m × 3 m is _________________.

Answer in One Word or a Line

1. Define volume. What is its standard unit?
2. What is a right circular cylinder? Give two examples.
3. Give the formula for finding the volume of a hollow cylinder.
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4. How many litres are there in 1 m ?
5. What is the formula for finding the length of the diagonal of a cuboid?

let’s evaluate
1. How many bricks will be required for a wall which is 4.9 m long, 8 m high and 2.4 m thick if each brick
measures 24 cm × 12.25 cm × 4 cm?
2. A swimming pool is 24 m long and 15 m broad. When few men dive into the pool, the height of the water
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rises by 1 cm. If the average amount of water displaced by one man is 0.1 m , how many men are there
in the pool?
3. If the length, breadth and height of a cuboid are in the ratio 6 : 5 : 4 and its total surface area is
2
33,300 m , find the dimensions of the cuboid.
4. A hollow cylindrical pipe open at both ends is made of 2 cm thick iron. If the internal diameter is 50 cm
and the length of the pipe is 140 cm, find the volume of iron in it.

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