Question

A wall 4 metre long, 3 metre high and 13cm thick is made up of bricks each measuring 20cm $ \times $12cm $ \times $6.5cm. The number of bricks required is
A. 500
B. 1000
C. 1500
D. 2000

Answer 1

Hint: In this question we will use some important formulae for finding the volume of the wall. Here we have given some parameters, we will use them to find out the volume of the wall and the volume occupied by a single brick and then we will divide the volume of the wall by volume occupied by a single brick.

Complete Step-by-Step solution:
We know that , a wall and a brick both looks as a cuboid in shape,
Volume of a cuboid = length $ \times $ breadth $ \times $ height . …….(i)
First we will find out the volume of the wall, we have
Length of wall = 4 metre = 4 $ \times $ 100cm = 400 cm
Breadth of wall = 13cm.
Height of wall = 3 metre = 3 $ \times $ 100cm =300 cm, now put these values in equation (i)
$ \Rightarrow $ volume of the wall = 400cm $ \times $ 13cm $ \times $ 300cm .
$ \Rightarrow $ volume of the wall = 1560000 cm$^3$. ……….(ii)
Now we will find the volume of one brick, we have
$ \Rightarrow $ Volume of brick = 20cm $ \times $12cm $ \times $6.5cm
$ \Rightarrow $ volume of brick = 1560 cm$^3$. ………(iii)
Now, dividing equation (ii) by equation (iii), we get
$ \Rightarrow $ number of bricks = \[\dfrac{{volume{\text{ }}of{\text{ }}the{\text{ }}wall}}{{volume{\text{ }}of{\text{ }}one{\text{ }}brick}}\].
$ \Rightarrow $ number of bricks = \[\dfrac{{1560000c{m^3}}}{{1560c{m^3}}}\]= 1000.
Therefore , the number of bricks required is 1000.
Hence, the correct answer is option (B).

Note: In this type of question, first we have to know what is given in the question and what we have to find. Here we have to find out the number of bricks required to make a wall of given parameters. Here we have found out the volume of the wall and then the volume of one brick. Then by dividing the volume of the wall by the volume of one brick ,we will get the total number of bricks required to make the wall.