Selected exercises
fill up a vacancy
1. The circumference of a circle is () times the diameter of this circle.
The circumference of a circle is () times the radius of this circle.
2. If the radius of the circle is enlarged by 2 times, the diameter of the circle is enlarged by () times and the circumference of the circle is enlarged by () times.
3, the circumference of a semicircle = ()
4, know the circle (), you can find the circumference of the circle.
5. Can you find out the track length of one revolution of the fan blade? How to ask?
6. The circumference of a circle with a radius of 3 decimeters is () decimeters.
7. The circumference of a semicircle with a diameter of 4 cm is () square cm.
8. Pi is 3. 14, right? ( )
Selected exercises ii
1. Find the circumference of the following circle (unit: cm).
1、r=2 r=3 r=5
2、d=2 d=3 d=5
Second, the application problem
1. The circumference of the circular pool in front of the exhibition hall is 78.5 meters. What is its diameter? What is the radius?
2. The radius of the front wheel of the road roller is 0.4m If the front wheel rotates 6 times per minute, it can turn from one end of the road to the other in ten minutes. How long is this road?
3. A 20-meter-long rope wound around the trunk six times, leaving 1. 16 meters. What is the diameter of the trunk?
4. The length of Ayong Road is 47. 1 meter. Xiaoming is rolling hoops on the road. The diameter of the iron ring is 30 cm. How many times does the hoop have to turn from one end of the road to the other?
Selected exercises 1
fill (up) a vacancy
1. The circumference of a circle is () times the diameter of this circle.
The circumference of a circle is () times the radius of this circle.
2. If the radius of the circle is enlarged by 2 times, the diameter of the circle is enlarged by () times and the circumference of the circle is enlarged by () times.
3, the circumference of a semicircle = ()
4, know the circle (), you can find the circumference of the circle.
5. Can you find out the track length of one revolution of the fan blade? How to ask?
6. The circumference of a circle with a radius of 3 decimeters is () decimeters.
7. The circumference of a semicircle with a diameter of 4 cm is () square cm.
8. Pi is 3. 14, right? ( )
Selected exercises ii
1. Find the circumference of the following circle (unit: cm).
1、r=2 r=3 r=5
2、d=2 d=3 d=5
Second, the application problem
1. The circumference of the circular pool in front of the exhibition hall is 78.5 meters. What is its diameter? What is the radius?
2. The radius of the front wheel of the road roller is 0.4m If the front wheel rotates 6 times per minute, it can turn from one end of the road to the other in ten minutes. How long is this road?
3. A 20-meter-long rope wound around the trunk six times, leaving 1. 16 meters. What is the diameter of the trunk?
4. The length of Ayong Road is 47. 1 meter. Xiaoming is rolling hoops on the road. The diameter of the iron ring is 30 cm. How many times does the hoop have to turn from one end of the road to the other?
Divide a circular piece of paper into several equal parts, then cut it open and spell it into an approximate rectangle. The length of this rectangle is equivalent to a circle () and the width is equivalent to a circle (). Because the area of a rectangle is () and the area of a circle is ().
3. Judges:
The formula for the area of (1) circle is s = πr2 or s=2πr ().
(2)r2=r×2()
(3) The circumference of a semicircle is equal to the circumference plus the diameter of the circle, so the area of the semicircle is equal to the length of the area plus the diameter of the circle. ( )
Selected exercise 4
1, select:
(1) If the diameter of a circle is equal to the side length of a square, then the area of the circle () the area of the square.
A: greater than b: equal to c less than.
(2) If the radius of a circle is enlarged by 3 times, then its area is enlarged by () times.
A: 3 times B: 6 times C: 9 times
(3) If the circumference of a circle is equal to the circumference of a square, then the area of the circle () the area of the square.
A: greater than b: equal to c less than.
2. Application questions:
(1) radius of automatic rotary sprinkler in the park10m. What is its maximum spray area?
(2) The perimeter of the lawn is 50.24 meters. How many square meters is this lawn?
(3) The circumference of a fish pond is100.48m, and there is an annular island with a radius of 6m in the middle. What is the water area of this fish pond?
(4) Saw the largest circle from a rectangular plate with a length of 5 decimeters and a width of 4 decimeters. How many square decimetres are the remaining boards?
1. A self-employed person earned 5,000 yuan in February last year and had to pay 3% business tax. How much money is left after tax?
2. In an alloy, the ratio of copper to zinc is 2: 3. Now add 6 grams of zinc to make a total of 36 grams of new alloy. Find the weight of zinc in new alloy.
As shown in the figure, on a circular clock face, the hour hand is 3 cm long and the minute hand is 5 cm long. /kloc-what is the area swept by the hour hand after 0/2 hours? How many centimeters did the minute hand go?
6. For the sake of students' health and safety, the school provides each student with a water cup, with a 10% discount on each water cup in Sanyuan and Ocean Mall, and "buy eight and get one free" in Baihui Commercial Building. The school wants to buy 180 cups. Please be a "staff officer" and calculate: which is more cost-effective? Please write down your reasons.
A village produced 40 tons of grain every year last year, an increase of 25% over last year. How many tons of grain will it produce this year?
8. There are 1200 fruit trees in the orchard, of which pear trees account for 40% and peach trees for 20%. How many fruit trees are there?
9. The road team has built a road, which has been repaired for 4.5 kilometers, and 55% has not been repaired. How many kilometers is this road?
10. 60% of chickens raised by Li are equal to 45% of geese. It is known that Uncle Li keeps 120 chickens, so how many geese does Uncle Li keep?
1 1. A batch of 540 saplings will be distributed to the fifth and sixth grade students for planting. There are 120 students in grade five and 150 students in grade six. How many saplings should you take in each grade if you allocate according to the number of people?
12. Li Shifu has processed a batch of parts, and the ratio of the number completed on the first day to the total number of parts is 1: 3. If 15 pieces are processed, half of this batch of parts can be completed. How many parts are there in this batch?
13. For a project, team A needs to do it alone 10 days, and team B needs to do it alone 15 days. After team A did it for two days, the rest were done by both teams. How many days will it take to complete this task?
14. Warehouse A stores 100 tons of grain, warehouse B stores 80 tons of grain, and warehouse A transports a batch of grain to warehouse B. At this time, the grain in warehouse B is just 45% of that in warehouse A. How many tons of grain did warehouse A transport to warehouse B?
15. The number of "qualified" students in grade five is more than that in grade four, and the actual number is 12. How many people are "up to standard" in the fourth grade physical education?
16. Xiaoming bought a three-year treasury bill with his lucky money 1300, with an annual interest rate of 5.85%. How much principal and interest will he get after three years?
17. The construction team built a highway, with the total length of 20% in the first week, the total length of the second week and the total length of two weeks180m. What is the total length of this highway?
18. The goods in the station are 90 tons, and two cars can be transported 12 times. A car alone will be transported 20 times. How many times can B car be transported alone?
24. The typist types a manuscript. On the first day, I typed 30 pages, and on the second day, I typed 20 more pages than on the first day. I finished typing this manuscript in two days. How many pages are there in this manuscript?
25. If a batch of goods is delivered on the first day, 14 tons will be delivered on the second day, and all the remaining 28 tons will be delivered on the third day. How many tons is this shipment?
26. Party A will finish a project within 20 days, and Party B will finish it within 30 days ... After Party A and Party B worked together for a few days, Party B asked for leave because of something, and Party A continued to work, which took a total of 16 days from the start to the completion of the task. B how many days off?
27.an.d reading a story book, five pages were missing on the first day, three pages were missing on the second day, and there were 206 pages left. How many pages does this story book have?
28. A batch of parts will be completed in 6 days by Party A, 9 days by Party B and 4 days by two people, leaving 260 parts. How many parts are there in this batch?
29. It is as simple as it can be.
6÷ +4÷ 4÷ - ÷4
× + ÷ 127 ÷( 23 — 14 )
30. Simplify the ratio and find the ratio
0.4∶
0.3 ton: 150 kg 0.6:
There are two water pipes in the swimming pool. The first water pipe can be filled with water within 10 hour when the pool is empty, and the second water pipe can be filled with water within 15 hour when the pool is full. Now, how many hours can an empty pool hold water?
32. From A to B, it takes 8 days for ship A and 12 days for ship B. Both ships leave from A at the same time. How many days is the distance between the two ships?
33. For a section of railway, the ratio of repaired length to unrepaired length is 4:5. If you build another 50 kilometers, the finished length will account for the whole length. How many kilometers is this railway?
34. The construction team built a section of highway, which was 320 kilometers beyond the midpoint when it was completely long. How many kilometers is this road?
35. Two ships A and B set sail from two ports at the same time. The whole journey takes 10 hour for a ship and 15 hour for b ship. Five hours later, the distance between the two ships is still 75 kilometers. How many kilometers are the two ports apart?
5 1, the total length of a cuboid is 220 cm, and the known ratio of length to width is 5:4:2. What is the volume and surface area of this cuboid?
52. Story books in schools account for the total number of school books. Bought 400 story books, story books accounted for the total. How many books were there in the school?
53. The part where the rope was cut was left. If 10 cm is cut off, the cut-off part is left. How many centimeters is this rope?
54. calculation
One number is 80. What is the number?
What is the quotient of the sum of 43 and its reciprocal divided by the product of 169 and 14?
60% of a number is 32, not 60% of 32. What's this number?
A number is 4 more than 2% of 20. What's this number?
1 7 ÷7+7÷ 1 7 6-( 1 7 ÷2+3)
55. A workshop plans to produce 360 parts, and 60 parts have been produced so far. How much will be produced in order to complete this plan?
56. Dig a kilometer of canal. What was dug in the first week was not dug, and another kilometer was dug in the second week. How many kilometers have you dug in two weeks?
57. Divide a one-meter hacksaw into five equal parts. What is the average length of each segment?
58. Build a dam. Team A built a full-length dam, which is exactly 360 meters. Team B built a full-length dam. How many meters did Team B build?
59. The smallest natural number among continuous natural numbers is equal to the sum of these five numbers. What are these five numbers? 、
60. A cup of salt water is 200g, in which the ratio of salt to water is 1:24. Now, how many grams of water is needed to dilute this cup of brine so that the ratio of salt to water is 1:29?
6 1. Uncle Wang sells pears, apples and oranges. Their weight ratio is 3:4:6, in which oranges are 80 kilograms more than apples. How many kilograms of pears are there?
62. Three young pioneers planted 100 castor seeds, of which A planted the total number, and the ratio of the number of trees planted by B to that planted by C was 7:5. How many castor beans did B grow more than C?
63. The distance between the two places is 630 kilometers. Two cars, A and B, leave the two places at the same time and meet in seven hours. The speed ratio between car A and car B is 4:5. How many kilometers do cars A and B travel per hour?
64. The newly harvested 500g wheat was 63.2g lighter after drying in the sun. What is the water content of this wheat?
72, a cylindrical steel, meters weight tons, existing steel 2 meters, how many tons?
73. There are 180 sheep grazing on the grassland, of which 29 are goats and the rest are sheep. What percentage of the total are sheep? How many sheep are there?
74. Yangshan Primary School participated in tree planting activities and distributed 240 trees to the fourth, fifth and sixth grades according to the ratio of 2: 3: 5. How many more trees were planted in the sixth grade than in the fourth grade?
75. A car travels from A to B, with an average speed of 80 kilometers per hour, which takes one hour and just completes the journey. How many kilometers is it from a to b?
76. Table tennis falls in the sky, and the height of each bounce is 25 of the falling height. If you fall from a height of 25 meters, what is the height of the second rebound?
77. The actual cost of a bridge is 2 1 million yuan, which is 1 million yuan more than the original plan. What was the original planned cost?
78. For a pile of coal, the ratio of tonnage transported on the first day to total tonnage is 1: 4. 4.5 tons were shipped the next day, and just 1.3 of the total tonnage was shipped in two days. How many tons is this pile of coal?
79. Two workshops 150 people. If 50 people are transferred from other places to the first workshop, the number of people in the first workshop is 2/3 of that in the second workshop. How many people are there in workshop 2?
80. Two cars, A and B, set off at the same time and walked in opposite directions. They met 56 stamps in 7 hours, and Xiaoming's stamps were 43 from Xiao Xin. How many stamps does Xiaoming have?
Column type:
(3) The actual investment of a project is 3.8 million yuan, which is 200,000 yuan less than the planned investment. What percentage was saved?
Column type:
(4) Team A completed a project in 50 days, while Team B completed it in 70 days. What is the ratio of team A and team B to complete this project every day?
Column type:
5] One-time deposit in the bank in 400 yuan for 5 years. If the annual interest rate is 2.88%, how much after-tax interest can you get at maturity?
Column type:
67. There is a circular fountain in the Oriental Plaza with a circumference of 37.68 meters. How many square meters is this fountain?
68. A has a house worth 300,000 yuan and sold it to B at a 10% discount (90%). After a period of time,
House prices rose 10%, and B was sold to A. How much did A lose?
69. The garment factory produces a batch of school uniforms, and the ratio of the number of sets completed before 10 to the total number of school uniforms is 1:3.
If 150 sets are produced, just 40% of this batch of school uniforms can be completed. How many school uniforms are there?
70. The number of peach trees belongs to pear trees, and the number of pear trees belongs to poplar trees. There are 30 peach trees known. How many poplars are there?
7 1. A piece of wood is 8 meters long. It accounts for 2/5 of the total length first, and then1/5m. How many meters does it need?