It is known that the density of bricks is 1.5 × 103 kg / m3. The walls of a house are built with bricks of 25 cm in length, 12 cm in width and 6 cm in thickness. If the total area of the internal and external walls of the house is 720 square meters and the thickness of the wall is 25 cm, the construction of the house will need bricks______ If the car can carry 4 tons at a time, it should be pulled at least______ It's only three times before you can pull these bricks

It is known that the density of bricks is 1.5 × 103 kg / m3. The walls of a house are built with bricks of 25 cm in length, 12 cm in width and 6 cm in thickness. If the total area of the internal and external walls of the house is 720 square meters and the thickness of the wall is 25 cm, the construction of the house will need bricks______ If the car can carry 4 tons at a time, it should be pulled at least______ It's only three times before you can pull these bricks

(1) Because the length of the brick is the same as the thickness of the wall, the inside and outside surface area of the brick is s = 2 × 0.12M × 0.06m = 0.0144m2; the total area inside and outside the wall is s = 720M2; so the total number of bricks required is n = s = 720m20.0144m2 = 5 × 104