1, a×b=c, when a is constant, a and b are in direct proportion, and when b is constant, it is in direct proportion.

2. When the sum is constant, the ratio of one addend to another.

3. If number A equals number B, the ratio of number A to number B is: If number A equals number B, the ratio of number A to number B is:

4. In a proportion, the product of two internal terms is the smallest composite number, one external term is 0.5 and the other external term is 0.5.

5.A: B =:, A and B are both natural numbers. Just rewrite the proportional formula into a multiplication equation.

6. Rewrite the line segment scale to digital scale.

7. If a = b, then (a-b a-b a-b a-b).

8, b÷5= a×, then the simplest ratio of a to b is. If 7a=5b, then = =

9. The ratio of quantity A to quantity B is 7: 5. If a is 2 1, then b is.

10, a 5 mm part, is drawn on a graph with a length of 10 cm, and the scale of this graph is.

The divisors of 1 1 and 12 are. Choose four of them and make them into proportions.

12, and the ratio of Party A to Party B is 5: 3. The number b is 60 and the number a is.

13, the distance of 20 cm on the map represents the actual distance 10 km, and the scale of this map is. Represented by line segment scale:; On the map, the distance on the map is 2 cm, and the actual distance is 0.

14. On the map with the scale of 1: 5000000, the distance from Shanghai to Hangzhou is 3.4 cm, and the actual distance from Shanghai to Hangzhou is.

Second, judge.

1, the natural number is inversely proportional to its reciprocal. ( )

2. In a proportion, if the product of two external terms is divided by the product of two internal terms, the quotient is 1. ( )

3. Because 3a = 4b, a: b = 3: 4. ( )

The area of a circle is proportional to the square of the radius. ( )

5. The first and last items of the ratio are multiplied by the same number at the same time, and the ratio remains unchanged. ( )

Third, judge whether the following two related quantities are proportional. If so, what percentage?

1, a cuboid has a certain volume, and its bottom area is the same as its height. ( )

2, the wheel diameter is certain, the distance traveled and the number of revolutions of the wheel. ( )

3. The area and radius of a circle. () 4. The circumference and diameter of the circle. ( )

5. If Y=5X, Y and x. () 6, a ×b=5, A and B. ()

7, the distance on the map is certain, the actual distance and proportion. ( )

8. People's weight and height. ( )

9. The price of each TV set must be fixed, the number of TV sets and the amount purchased. ( )

10, covering a certain area, the area of bricks and the number of bricks used. ( )

1 1, the area of bricks is fixed, the occupied area and the number of bricks used. ( )

12, one factor is affirmative, product and another factor. () 13, and some, addend and another addend. ( )

14, the circumference of a rectangle is fixed, and its length and width are constant. ( )

15, the area of a rectangle is certain, and its length and width. ( )

16. The number and amount of subscriptions to China Youth Daily. ( )

Fourth, the application problem.

1. On the map, the line segment with the length of 14cm represents the actual distance of 4900km. Find out the scale of this map.

On the map of 1: 50000, the distance between the two places is 3.2 cm. What is the actual distance between the two places?

3. The teaching building base of Juyu Primary School is rectangular, with a length of 72m and a width of 14m. Draw it on the map with a scale. What is the length and width of the rectangle on the picture? What is the area? Draw the floor plan of the teaching building.

There is a kind of clothes in the shop, which is 25% cheaper in 96 yuan. How much cheaper is the current selling price than the original pricing? 780 yuan used it to buy 3 barrels of oil for the canteen. According to this calculation, how much does it cost to buy 8 barrels of oil?

5. A salt drying field can dry 3 grams of salt with 100 grams of seawater. If you put 585,000 tons of seawater into a salt pan at a time, how many tons of salt can you dry?

6. The house is paved with square bricks. It needs 96 square bricks with an area of 9 square meters. If it is replaced by a square brick with an area of 4 square meters, how many pieces are needed?

7. It costs 2000 yuan to floor the classroom with a square brick with a side length of 15cm. How many pieces do you need if you replace it with a square brick with a side length of 25 cm?

8. It takes 10.6 hours for a scientific experimental satellite launched by China to orbit the earth six times in the air, and how many hours does it take to run 14 weeks?

A pesticide is prepared from liquid medicine and water according to the ratio of1:1500. (1) How many kilograms of liquid medicine and water does it take to prepare 750.5 kilograms of this pesticide? (2) At present, only 540 kilograms of water is available. How many kilograms of liquid medicine does it take to prepare this pesticide?

9. The school playground is rectangular, with a length of 120cm and a width of 75cm. Draw a plan with a scale of 1: 3000. How many centimeters are the length and width?

10. On Arbor Day, students assign tasks in groups. It is known that the working ratio of the first, second and third groups is 5: 3: 4. If the first group planted 15 trees, how many trees did the third group plant?

1 1. Animal Anecdotes has 120 pages, with 25 lines per page and 32 words per line. If it is modified to 30 lines per page, how many pages should 40 words per line be?

12. The municipal workers laid the floor tiles for the newly-built music square, and laid 6150m2 three days ago. At this rate, it will take another five days to finish the task. How many square meters is the floor tile area of Music Square?