16 ÷ (3- 1) = 8 (cubic decimeter)
8× 3 = 24 (cubic decimeter)
2. Cylinders and cones have the same volume and the same bottom area. The height of the cylinder is 12 decimeter, so the height of the cone is (36) decimeter. (column calculation)
12×3=36 (decimeter)
3. The volume and height of the cylinder and the cone are equal, and the bottom area of the cone is 9 square decimeters, so the bottom area of the cylinder is (3) square decimeters.
9÷3=3 (square decimeter)
4. Basic knowledge
(1) The bottoms and heights of the cylinder and the cone are equal, and the volume of the cone is small 8 square decimeter of the cylinder, so the volume of the cylinder is (12) cubic decimeter, and the volume of the cone is (4) cubic decimeter.
(2) The cylinder and the cone have the same bottom and the same height, and their volumes are 60 cubic centimeters, so the volume of the cylinder is (45) cubic decimeter.
③ The area and height of cylinder and cone are equal. The volume of a cylinder is 6 cubic centimeters, and the volume of a cone is (2) cubic centimeters.
④ The bottom area and volume of cylinder and cone are equal, the height of cylinder is 6 cm and the height of cone is (18) cm.
⑤ The height and volume of the cylinder and the cone are equal, the bottom area of the cone is 6 square centimeters, and the bottom area of the cylinder is (2) square centimeters.
⑥ Cut the cube with the side length of 10 cm into the largest cylinder. The volume of this cylinder is (250π π π π, if we take 3. 14, it is 785) cubic centimeters, (1000-250 π π π π, if we take 3. 14, it is 265438.
① A pile of conical sand piles with a bottom area of15m2 and a height of1.2m.. Use this pile of sand to pave a 2 cm thick sand road on a 3 m wide path.
15×1.2 ÷ 3 ÷ (3× 0.02) =100 (m)
Answer: A road with a length of 100 meters can be paved.
(2) Dissolve and hoe a conical steel block with a bottom diameter of 8 decimeters and a height of 6 decimeters into a cuboid. This rectangle is 4 centimetres long and 2 centimetres wide. What is its height?
8÷2=4 (decimeter)
π×4×4×6÷3=32π (cubic decimeter)
32π\(4×2)= 4π (decimeter)
If π in the above question takes 3. 14, the formula is:
3.14× 4× 6÷ 3 =100.48 (cubic decimeter)
100.48 (4× 2) =12.56 (decimeter)
A: Its height is 12.56 (decimeter).
1. A cylindrical bucket with a ground diameter of 20cm and a water depth of 30cm. Put a steel block and the water level will rise by 5 cm. What is the volume of this iron block?
20 ÷ 2 = 10 cm
3.14×10×10× 5 =1570 cubic centimeters.
Answer: The volume of iron is 1570 cubic centimeters.
2. A cylindrical bucket with a bottom diameter of 20 cm and a water depth of 30 cm. When a steel cone with a bottom radius of 5 cm is placed, the water level rises by 2 cm. How high is this cone?
20 ÷ 2 = 10 cm
3.14×10×10× 2 = 628 cubic centimeters.
628÷3. 14÷(5×5)×3=24 cm
This conical part is 24 cm high.
3. After a cube container with a length of 4 decimeters is filled with water, pour the water into a conical container with a bottom area of 48 square decimeters, and it is just filled. What is the height of this conical container?
4×4×4=64 cubic decimeter
64-48× 3 = 4 decimeters
A: The height is 4 decimeters.
Unit 1 examination questions
First, the number written directly is16x20% = 3.225% = 2.520x3/2 = 30. Fill in the blanks 1. 16 is 20 (80) 20 is 16%, (1.25) 65433. 20 is (25)% more than 16. 3/8x8/3 = 1 36x 5/6 = 30 12x 30% = 3.6 10x。
40% of 2( 60) tons is 24 tons. 3. 20% less than 30 meters is (24)m. 3, the sum of two numbers of A is 39, the number of A is 30% of the count, the number of A is (9), and the number of A is (30).
4. The number of parts produced by a parts factory in March is 87.5% of that in February, so the number of parts produced by the factory in March is less than that in February (12.5)% 5. The number of roosters in Hongxing Farm is 50% of that of hens, so the number of roosters accounts for (33.3 )% of the total number, and the number of hens accounts for (66.6 )% 6. The preferential activities during the Spring Festival are 20% off. Only (384) yuan is needed after the discount. 7.4: 5 = (8): (10) = (0.8) = (80)% = (8) discount.
True or false: 1 The price of a commodity first decreased by 10%, and then increased by 10%. The current price of this commodity is equal to the original price (×) 2. Put 15g salt into 100g water, and the salt content of the brine is 15%.
There are 25 boys and 22 girls in (×)3 6 1 class. There are more boys than girls 15%. 4 (√) 5 (×) 4. Multiple choice questions, 1. Aunt Wang now deposits 5000 yuan in the bank for three years, with an annual interest rate of 5.4%. After the maturity, she will get interest from the bank (a) A5000x5.4% X3B 5000x5.45% C5000x5.40% XX5D5000+3. The number of nails is 25% more than nails, and the number of nails is 25% (×) less than nails.
Divide a Woodenhead into five sections, each of which is 20% of Woodenhead.
A commodity is sold at a 30% discount, which is cheaper than the original one. 75 yuan, this product was originally (C) yuan, A 525 B 225 C 250 D 150.
3 A rope used 2 meters, and the rest used 25%. This rope is (c) meters long. A 0.5 B 2 C 2.5 D are all wrong.
4 250m is less than 65 438+0km (C) A 25% B 33% C 40% D 75%.
The school plans to invest 4.8 million yuan to build a comprehensive teaching building, which is actually 35% less than planned. The actual investment saved (b) ten thousand yuan. a 480 x35 % B 480 x( 1-35%)C 480/35% D 480/( 1-35%)
I have read 20 pages of a story book, and there are 60 pages left. People who haven't read this book account for 25% B 33% C 66% D 75%.
The sales of a toy factory in 2008 was 52 million yuan. If the consumption tax is paid at 5% of the sales, the toy factory will pay the consumption tax (A) 10000 yuan in 2008. a 5200 X5 % B 5200 x( 1-5%)C 5200/5% D 5200/( 1-5%)
After the book written by Zhang Ming was published, the manuscript fee was 2600 yuan. According to the regulations, 20% personal income tax shall be paid for the part of the manuscript fee that exceeds that of 800 yuan. After paying taxes, Zhang Ming's contribution fee is (a) A2600-(2600-800) X20% 2600x (1-20%) B2600-2600x20% C.