How many bricks, each measuring $$25\ cm\times 11.25\ cm\times 6\ cm$$, will be needed to build a wall $$8\ m$$ long, $$6\ m$$ high and $$22.5\ cm$$ thick?
Correct option is C. $$6400$$
We know that the volume of cuboid $$= length\times breadth \times height$$
So,
Volume of brick $$=25\ cm \times 11.25\ cm \times 6\ cm$$
$$=1678.5\ cm^3$$
And volume of the wall $$=80\times 60\times 22.5$$
$$=10800000\ cm^3$$
So, the number of bricks $$=10800000/1678.5=6400$$