A rectangular box, 5 cm long, 4 cm wide and 13 cm high. How many square centimeters of material does it need?
(7× 4+7×10+4×10) × 2 = 276 (written by the company itself)
A 30-meter-long steel pipe was sawed into three sections. 1 section is 7 meters long and 2.5 meters shorter than the second section. How many meters is the third section?
30-7-(7+2.5)= 13.5
There is 2 100 cubic meters of water in the middle of the rectangular pool, which is 50 meters long and 20 meters wide. How deep is it?
2 100÷50÷20=2. 1
I have something to do today. I'll send it later.
Pick it up ~
Teams at all levels make a rectangular frame with 60 cm wire, which is 6 cm long, 5 cm wide and how many cm high?
60-6×4-5×4= 16 16÷4=4
A bunker is 2.5m long,1.5m long and 0.6m deep. How many cubic meters of sand does it take to fill this bunker?
2.5× 1.5×0.6=2.25
A cuboid bucket without a lid, the bottom of which is a square with a side length of 4 decimeters and a height of 5 decimeters, how many decimeters of iron sheet is needed to make it?
4×4+4×5×4=96
A square with a side length of 4 decimeters, fill the fish tank with water and pour it into another square, which is 4 decimeters long and wide. How deep is the fish tank?
4× 4× 4÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷÷
In a cubic water tank, each side is 4 centimetres long. At night, how deep is the water in another tank 8 cm long and 25 cm wide?
25 cm =2.5 decimeter 4× 4× 4 = 64,64 ÷ 8 ÷ 2.5 = 3.2.
A car consumes 4/5 kilograms of fuel every 8 kilometers. How many kilometers can you drive per kilogram of oil on average? Ok, how much fuel does 1 km consume?
8÷4/5= 10，4/5÷8=0. 1 kg。
There are 49 students in one class, including 24 boys. What percentage of boys are in this class? What percentage of girls are in the class?
The number of boys divided by the class size is 24/49=49%.
Female: 49-24=25 (person) 25/49=5 1%
Answer: Boys account for 49% of the class and girls account for 5 1% of the class.
6. A 30-meter-long steel pipe was sawed into three sections. The first section is 7 meters long and 2.5 meters shorter than the second section. How long is the third section?
30-7-(7+2.5)
=23-9.5
=13.5m
Answer: The third section is13.5m..
7. There is a swimming pool, which is 25m long,12m wide and1.4m deep. Square white tiles with a length of 2 meters are attached to the bottom and edge of the pool. A * * *, how many pieces do you need?
Because the swimming pool has no roof.
So 25m=250.
12m = 120m。
1.4m= 14 decimeter
250 *120+120 *14 * 2+250 *14 * 2 = 30360 square decimeter.
A tile is 2 2 = 4 square decimeters.
So a * * * uses 30360/4=7590.
8. An engineering team built a highway with a length of 15.8km, the first perimeter was 5km, and the second week was 0.7km more than the first week. How many kilometers will it take to complete?
Five and three quarters = 5.75 kilometers.
15.8-5.75-(5.75+0.7) = 3.6 km.
A: It will take 3.6 kilometers.
9. This cuboid reservoir has 2 100 cubic meters of water. This reservoir is 50 meters long and 20 meters wide. How deep is it?
2 100÷50÷20=2. 1
10. The school brought 7.6 cubic meters of sand and spread it in a bunker 5 meters long and 3.8 meters wide. How thick can it be laid?
5x3.8= 19 (square meters) 7.6 divided by 19=0.4 (meters).
Answer: it can be 0.4 meters thick.
1 1. A water conservancy engineering team repairs ditches every day for the first four days 125m, and repairs ditches every day for the last three days 134m. How many meters of canals does this engineering team build on average every day?
( 125/4+ 134/3)/2=9 1 1/24
12. How long does it take to make 10 cubic iron frame with a side length of 8 cm?
12*8* 10=960 cm
13. Make an iron box with iron sheet so that its length, width and height are 1.8 decimeter, 1.5 decimeter and 1.2 decimeter respectively. How many square meters does it take to make such an iron box?
That is to say, find its surface area
2x (1.8x1.5+1.8x1.2+1.2x1.5) =13.32 (decimeter).
Answer: To make such an iron box, at least 13.32 decimeter iron sheet should be used.
14. How many square meters of glass does it take to make a cubic glass fish tank without a cover? The side length is 3 meters.
Since 3*3*5=45 (square decimeter) is not covered, there is no need for an upper surface, only five surfaces are needed, and then the area of one surface is calculated first, and then multiplied by five.
15. 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, we know that every square meter needs 5 yuan painting fee. How much does it cost to paint a classroom?
8 * 7+8 * 3.5 * 2+7 * 3.5 * 2-13.8 =147.2 square
147.2*5=736 yuan
16. A commodity box is a cube with a side length of 6 cm. What is the maximum area of a box with a trademark?
Put the trademark on the four sides of the cube, so that the largest area is 6*6*4= 144 square centimeter.
17. Make drawers with the length, width and height of 2.8 decimeters, 1.5 decimeters and 2.2 decimeters respectively. How many square meters of wood does it take to make five such drawers?
Analysis: In fact, it is to find the surface area. Tip: The drawer only needs 5 sides, and there is no top.
Surface area of
2.8× 1.5+(2.8×2.2+ 1.5×2.2)×2
=4.2+ 18.92
= 23.12m2
Surface area of 5 drawers
23.12× 5 =115.6 m2
18. There is a fish pond, which is 18 m long, 12 m wide and 3.5 m deep. It is necessary to coat a layer of cement around the fish pond to prevent water seepage. How many kilograms of cement do you need if you use 5 kilograms of cement per square meter?
18x12+18x3.5x2+12x3.5x2 = 426 square meters.
426 x 5 = 2 130 kg
19. The processing factory will process a batch of TV sets. (No bottom) Each TV is 60 cm long, 50 cm wide and 55 cm high. How many square meters of cloth does it take to make 1000 sets?
60×55 = 3630 cm2 60×50×2+55×50×2 = 1 1500 cm2
(11500+3630) ×1000 = 15 130000 square centimeters =1513 square meters.
20.24 rectangular iron chimneys, each 2m long, 4m wide and 3m high. How many square meters of iron do you need?
The surface area of each tin chimney is:
2×(2×0.4+2×0.3)
=4×0.7
= 2.8 square meters
The surface area of 24 chimneys is 2.8× 24 = 67.2 square meters.
At least 67.2 square meters.
2 1. A rectangular goldfish bowl, 8 centimetres long, 5 centimetres wide and 6 centimetres high, accidentally broke the glass in front of it. When repairing the glass, how many square decimeters is the area of the glass?
8x6=48 (square decimeter) =48000 (square centimeter) =0.48 (square meter)
The nominal area unit is decimal.
22. The rectangle is 4 decimeters long, 2.5 decimeters wide and 3 decimeters high. How many cubic decimeters is its volume?
1. Volume =4×2.5×3=30 cubic decimeter.
23. A cuboid bunker is 4m long, 2m wide and 0.5m deep. If the yellow sand weighs 1.4 tons per cubic meter, how many tons does it weigh?
Yellow sand weight =4×2×0.5× 1.4=5.6 tons.
24. There is a rectangular steel with a length of 2 meters, a square cross section and a side length of 5 cm. Each cubic decimeter of steel weighs 7.8 kilograms. How much does this square steel weigh?
Weight of each piece: 7.8x0.05x0.05x2=0.039 ton.
100 pieces weigh 3.9 tons.
A cuboid with a bottom area of 30 square decimeters and a height of 3 meters, what is its volume in cubic decimeters?
Square decimeter (bottom area) ×30 decimeter (height) =900 cubic decimeter.