Question

Q1 A brick measures 24 cm x 12 cm x 8 cm. How many bricks will be required to construct a wall measuring 24 m long, 8 m high and 60 cm thick?

Q2. Two cubes each of volume 512 cm3 are joined end to end. Find the surface area of the resulting figure.

Q3. An aquarium is in the form of a cuboid whose external measures are 80 cm x 30 cm x 40 cm. The aquarium has to be covered with a coloured paper (except its top and front). Find the area of the paper needed?

Q4. 10 cylindrical pillars of a building are to be painted. If the diameter of each pillar is 50 cm and the height is 4 m then, what will be the cost of painting them at the rate of ₹14 per square meter.

Q5. A solid iron rectangular block of dimensions 4.4 m, 2.6 m and 1 m is cast into a hollow cylindrical pipe of internal radius 30 cm and thickness 5 cm. Find the length of the pipe.

Q6. Verify Euler’s formula for Tetrahedron.


Q7. A person pays ₹2200 to some people to paint the inner curved surface area of a cylindrical vessel 10m deep. If the cost of painting is at the rate of ₹20 per m², find

(a) the inner curved area of the vessel.

(b) the radius of the base.

Q8. Water in a river, 2m deep and 45m wide, is flowing at the rate of 3 km per hour. Find the amount of water in cubic meters that runs into the sea per minute.



Q9. If a polyhedron has 6 faces and 8 vertices, then how many edges does it have?



Q10. The dimensions of a cuboid are in the ratio 1: 2: 3 and its total surface area is 88 m². Find the dimensions.

Q11. The diameter and length of a roller are 70 cm and 100 cm respectively. It moves once over to level a playground of area 4400 m². Find the number of revolutions the roller will take to level the playground.

Answer 1

Answer:

Firstly we'll convert each of them into cm.

So, new dimensions of the wall are,

2400cm*800cm*60cm

Total volume of the wall= 2400*800*60 cm³

=115,200,000cm³

But 10% of this volume is occupied by the mortar, hence we are left with it's 90% of volume.

Therefore, 115,200,000*90/100

=10,368,000 cm³ is the final volume of the wall.

Volume of the brick=24cm*12cm*8cm

=2,304cm³

Number of bricks= Volume of wall/Volume of bricks

=10,368,000/2, 304

=4500 bricks

Therefore 4500 bricks will be required.