Question

how many bricks do we need to build a wall that is 7m long 15 cm wide and 8 m high if each brick ha length 20 cm breadth 10 cm and height 5 cm

Answer 1

Answer

Dimention of Wall;

l=8m=800cm

h=6m=600cm

b=22.5cm

volume of the wall =lbh=800×600×22.5

=10800000cm

3

Dimention of brick;

l=25cm

b=11.25cm

h=6cm

volume of brick =lbh

=25×11.25×6

=1687.5cm

3

therefore number of bricks=volume of wall/volume of 1 brick

=

1687.5

10800000

=6400 bricks

Therefore number of bricks are 6400.

Answer 2

⇒ Final Answer:

8400 bricks

⇒ Given:

Length of wall = 7 m

Breadth of wall = 15 cm

Height of wall  = 8 m

Length of brick = 20 cm

Breadth of brick = 10 cm

Height of brick = 5 cm

⇒ To Find:

No. of bricks required to build the wall of given dimensions.

⇒ Analysis:

First of all, we need to convert all the dimensions of the to cm and then find the volume of the wall. Next, we need to find the volume of one brick and then divide the volume of one brick from the total volume of the wall.

⇒ Formula to be used:

$\boxed{\sf{Volume\:of\:cuboid=lbh}}$

⇒ Solution:

First we can find the volume of the wall:

Length = 7 m = 700 cm

Breadth = 15 cm

Height = 8 m = 800 cm

Volume of the wall = lbh

= 700 x 800 x 15

= 8400000 cm³

Now, the volume of one brick:

Length = 20 cm

Breadth = 10 cm

Height = 5 cm

Volume of the brick = lbh

= 20 x 10 x 5

= 1000 cm³

No. of bricks required:

$\sf{=\dfrac{Volume\:of\:wall}{Volume\:of\:one\:brick}}$

$\sf{=\dfrac{8400000}{1000}}$

$\sf{=8400\:bricks}$

Hence 8400 bricks are required.

Knowledge Bytes:

→ Cuboid

A cuboid is a 6 faced 3D figure made up of rectangles. It has 12 edges and 8 vertices.

$\setlength{\unitlength}{0.74 cm}\begin{picture}\thicklines\put(5.6,5.4){\bf A}\put(11.1,5.4){\bf B}\put(11.2,9){\bf C}\put(5.3,8.6){\bf D}\put(3.3,10.2){\bf E}\put(3.3,7){\bf F}\put(9.25,10.35){\bf H}\put(9.35,7.35){\bf G}\put(3.5,6.1){\sf x\:cm}\put(7.7,6.3){\sf y\:cm}\put(11.3,7.45){\sf z\:cm}\put(6,6){\line(1,0){5}}\put(6,9){\line(1,0){5}}\put(11,9){\line(0,-1){3}}\put(6,6){\line(0,1){3}}\put(4,7.3){\line(1,0){5}}\put(4,10.3){\line(1,0){5}}\put(9,10.3){\line(0,-1){3}}\put(4,7.3){\line(0,1){3}}\put(6,6){\line(-3,2){2}}\put(6,9){\line(-3,2){2}}\put(11,9){\line(-3,2){2}}\put(11,6){\line(-3,2){2}}\end{picture}$

→ Formulae related to cuboid:

✳ LSA = 2 (lh + bh)

✳ TSA = 2 (lh + bh + lb)

✳ Volume = lbh