Our school will paint the classroom, which is 8 meters long, 7 meters wide and 3 meters high. After deducting the area of doors, windows and blackboards, it is known that 5 yuan painting costs per square meter. How much does it cost to paint a classroom?

A commodity box is a cube with a side length of 6 cm. What is the maximum area of a box with a trademark?

5. How many cuboid blocks with a length of 8cm, a width of 12cm and a height of 5cm can be sawed into cubes with a length of 2cm?

6. A rectangular piece of wood with a square bottom is 5 meters long. Cut into 4 sections to increase the surface area by 36 square meters. What is the volume of this cuboid?

7. A rectangular iron plate with a length of 40 cm and a width of 30 cm, the four corners are cut into squares with a side length of 4 cm, and then welded into a box without a cover. How many liters is its volume?

8. As we all know, a rectangular tin tank with a length of 18 decimeter and a width of 10 decimeter can hold 1620 liters of water. How deep is this tank?

9. Rectangular plastic box with liquid medicine, 0.6m long, 0.25m wide and 0.5m deep. If you put the whole box of medicine into a small bottle with a capacity of 400ml each, how many bottles can this box hold at least?

10, a cubic billet is 6 decimeters long and forged into a square cuboid steel with a cross section of 3 centimeters. How many meters is steel?

1 1. A cuboid oil drum with a bottom area of 18 square decimeter can hold 43.2 kilograms of oil. If each liter of oil weighs 0.8 kg, what is the height of the oil drum?

12. In a glass jar with a length of 25 cm and a width of 20 cm, there is a cubic iron block with a length of 10 cm. At this time, the water depth is 15 cm. If the iron block is taken out of the jar, how many centimeters is the water depth in the jar?

13, a cuboid oil tank with a square bottom and a side length of 6 decimeters measured from the inside. It contains 144 liters of oil. As we all know, the depth of the oil inside is half that of the oil tank. How many decimetres is this oil tank?

14. One room 1200 wooden floor, 40 cm long, 20 cm wide and 2 cm thick. How many square meters is this room? How many cubic meters of wood does it take to spread out this room?

15 ... It takes 1000 to pave an auditorium with rectangular bricks with a length of 0.2m and a width of 0.1m.. How many bricks do you need if you use 0.0 1 m2 square bricks instead?

16. Make an uncovered cuboid oil drum with iron sheet. The length and width are 4 decimeters and the height is 6 decimeters. How many square decimetres is the iron sheet? Put gasoline in a barrel, and each liter of oil weighs 0.82 kg. How many kilograms of gasoline can this barrel hold?