Question

5. Find the number of bricks, each measuring 25 cm x 12.5 cm x 7.5 cm, required to construct
a wall 6 m long, 5 m high and 50 cm thick, while the cement and the sand mixture occupies
1
th of the volume of the wall.
20​

Answer 1

Question :-

Find the number of bricks, each measuring 25 cm×12.5 cm×7.5 cm required to construct a wall 6m long, 5m high and 0.5m thick, while the cement and sand mixture occupies 1/20th of the volume of the wall.

Given :-

Brick measurement :- 25×12.5×7.5 cm

Wall measurement :- 6×5×0.5 m

To find :-

No. of bricks needed to construct required wall.

Solution :-

Volume of wall = lbh = 6 × 5 × 0.5 = 15m^3

Given that Cement and sand mixture occupies 1/20th of the Volume of the wall.

Therefore, the volume of the wall occupied by the bricks :-

$(1 - \frac{1}{20} )$

and, Volume of wall =

$\frac{19}{20} \times 15 = 14.25 \: {m}^{3}$

Now, Volume of each brick =

$\frac{25}{100} \: m \times \frac{125}{100} \: m \times \frac{75}{100} \: m$

So, the bricks required :-

$\frac{volume \: of \: wall}{volume \: of \: each \: brick}$

$\frac{14.25}{ \frac{25}{100} \times \frac{125}{100} \times \frac{75}{100} } = 6080$

Hence, 6080 bricks of given dimension are required !

Answer 2

First of all we will calculate the volume of a single brick=25*12.5*7.5

                                                                                            =2343.75

Next we will calculate the volume of the wall=600*500*50                                

(I have written 6m as 600 cm and 5m as 500cm beacuse while calculating the volume of a single brick i took the dimension in cm)

                                                                           = 15000000 cm(cube) or cm^3

then we will find out the volume left for the bricks=

As 1/20th is covered by cement and sand

hence volume left for bricks=19/20 * 15000000 cm^3

                                               =14250000 cm^3

hence we will calculate the number of bricks required by dividing above left volume by the volume of single brick=14250000/2343.75

                                                              =6080