⑴ 12÷20=()∶5= =()%。

There are 28 boys and 25 girls in one class. The ratio of boys to girls is (), and the ratio of boys to the whole class is ().

(3)4.2:2.8 The simplest integer ratio is (), and the ratio is ().

(4) It takes 4 hours for Party A and 5 hours for Party B to make a batch of parts. The efficiency ratio of Party A and Party B is (), and the ratio is ().

5] The ratio of the two ratios is, and the ratio of the internal term to 6 and 5 is ().

⑹6∶4=3∶( ), ( )∶ =5∶

Once the scale of the map is, 1 cm on the map represents the actual distance () kilometers. On this map, the distance between A and B is 3.2 cm, and the actual distance is ().

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Pet-name ruby a drawing of precision instruments, with 5 cm long said the actual length is 5 mm, then the scale of this picture is ().

⑽ The numbers 15, 30, 6 and 3 can form four proportions, namely: (), (), () and ().

⑾ The circumference is proportional to its diameter ().

⑿ The circumference of a square is proportional to the length of the side ().

Second, the judgment question. (2 points for each question, *** 10)

(1) In a proportion, the product of two internal terms is subtracted from the product of two external terms, and the result is 0. ()

In the scale, the distance on the map is always smaller than the actual distance. ()

(3) The circumference of a rectangle is fixed, and its length and width are inversely proportional. ()

(4) The area of a circle is proportional to its radius. ()

5] Equations and proportions are equations. ()

Third, multiple choice questions. (2 points for each question, *** 10)

The first term of (1)a ratio is reduced by 3 times. To keep the proportion unchanged, the last item should be ().

A. Expand by 3 times B. Reduce by 3 times C. Keep unchanged

(2) The floor space is fixed, and (2) it is inversely proportional to the number of bricks used.

A. the side length of each brick B. the area of each brick C. the circumference of each brick

(3) Among the following proportions, two proportions in group () can form a proportion.

①5∶6 and 6∶5② and ③8∶7 and 2∶ 1.75.

(4) If 3a=4b, then a: b = ().

①3∶4②4∶3③3a∶4b

5] If the number of A equals the number of B, then the number of A: the number of B = ().

① : ② 15:8③ 8: 15

Fourth, calculation. (***20 points)

1, simplifying the ratio. (2 points for each question, ***8 points)

⑴ ⑵ 12∶2.4

⑶ ∶ ⑷ 2∶

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3. Solution ratio. (3 points for each question, *** 12 points)

⑴ 5∶8 = 20∶X⑵ =

⑶ : = X : ⑷ :X = :2

Fifth, solve the problem. (6 points for each question, ***30 points)

The swimming pool in the school is a rectangle, 25 meters long and 8 meters wide. Draw its plan according to the scale of.

(2) The ratio of the degrees of the two acute angles of a right triangle is 3: 6. How many degrees are these two angles?

(3) A and B are 440 kilometers apart. A car traveled 240 kilometers from A to B in three hours. According to this calculation, how many hours will we get to B? (Use proportional solution)

(4) An engineering team laid a section of sewer, originally planned to lay 20 meters a day, which was completed in 15 days. Actually paving 5 meters more every day, how many days did you actually complete the task? (Use proportional solution)

5] A rectangular piece of land with a perimeter of 120m and an aspect ratio of 5: 3. Find the area of this rectangular land.

Expand one's knowledge

"Ratio and proportion" test questions

1. Girls in a school account for 5 1% of the total number of students in the school. If there are 735 boys in this school, how many girls are there in this school?

2. If 3a = 4b and 5b = 6c, how many times is A greater than C?

3, a supermarket to carry out promotional activities, the original 10% off sales of eggs to 20% off sales. In this way, you can spend less 1.75 yuan if you buy 5 kg of eggs at a time. How much is the original price of that egg a catty?

4. The price of a commodity is 25 yuan/piece, so a 20% discount is required, and the price will be reduced after 2 yuan.

5. The purchase price of goods is one yuan/piece, and the price of goods in the peak season of sales is 50% higher than the purchase price; After the peak sales season, the products are promoted at a price of 30%. At this time, the price of a product is ().

(A) 1.5a(B)0.7a(C) 1.2a(d) 1.05 A

6. Bend a 24 cm long iron wire into a rectangle, length: width = 5: 1, and find the area of this rectangle.

7. A traditional Chinese medicine contains four herbal components: A, B, C and D. The weight ratio of these four components is 0.7: 1: 2: 4.7. Now, how many grams of these four herbs do you need to prepare 2100g of this Chinese medicine?

8. Draw ray OC with right angle ∠AOB. If ∠AOC: ∠BOC=3:2, find the degree of ∠BOC.

9. The ages of A, B and C are related as follows: A is twice as old as B, and C is 10 times, while last year, B was six times as old as C. What are the ages of three people?

10, the class committee decided that Dabao and Bauer would be responsible for buying 22 ballpoint pens and pens and giving them to the students in the paired mountain schools. They went to the mall and saw each 2 yuan for ballpoint pens and each 6 yuan for pens. If you buy a 10% discount ballpoint pen and a 20% discount pen, please write a purchase plan on the premise that the required cost does not exceed that of 60 yuan.