Question

do it fast with explaination

Answer 1

Dimensions of brick = 20cm×10cm×10cm
We know that brick is in the shape of cuboid.
Therefore,volume of brick=20×10×10
=2000cm^3
=20m^3
Dimensions of wall=12m×30cm×3m
=1200cm×30cm×300m
A wall is also in the shape of cuboid.
Volume of wall=1200×30×300
=10800000cm^3
=108000m^3
10%of wall consists of mortar.
Portion of mortar in wall=10/100×108000
=10800m^3
Portion of wall left=108000-10800
=97200m^3
Number of bricks required=volume of wall without mortar/volume of brick
=97200/20
=4860
Hence total number of bricks required to build the wall=4860.

Answer 2

volume of one bricks = l× b × h

= 20 × 10 × 10 cm³ = 2000 cm³

volume of wall = L × B × H

= 12 × 3 × 30/100 = 12 × 3 × 0.3 = 10.8 m³

but 10% of wall comprised of motor
so,

rest volume of wall which is formed by bricks = 10.8 - 1.08 = 9.72 m³

now,
number of bricks = volume of wall formed by bricks /volume of each brick

= 9.72 /2000 × 10^-6

= 9720000/2000

=9720/2 = 4860

hence, number of bricks = 4860