First, sit in the right position.
1, choose four numbers from divisor 30 to form the ratio of ().
2. If a:b=59, then a:5= (): ().
3. In the proportion, two external terms are reciprocal, one is 38 and the other is ().
4. According to 4.5×2=9× 1, write a minimum ratio ().
The actual distance from Beijing to Tianjin is 120km. On the map with the scale of 15000000, the distance between the two places is ().
6. If A and B are in direct proportion, then A is expanded by 4 times, then B (); If A and B are inversely proportional, then A is reduced by 8 times, then B ().
7. If X and Y are inversely proportional, when X= 15, Y = 5；; If X=2.5, Y= ().
8. If 16 of the apple weight is equal to 20% of the orange weight, then the ratio of the apple weight to the orange weight is ().
Second, choose to fill in.
The ratio of 1 to energy pair 15: 13 is ().
( 1) 13 : 15 (2) 3:5 (3)5:3 (4) 15 : 1 15
2. The total number of students in a school is certain, and the number of boys and girls is ().
(1) is directly proportional (2) is inversely proportional (3) is out of proportion.
3. Rewriting line segment scale to digital scale is ().
( 1) 1:50 (2) 1:200 (3) 1:20000000 (4) 1:5000000
4. Draw a part with a length of 5 mm on the drawing with a length of 10 cm. The scale of this picture is ().
( 1) 12 (2)2 1 (3) 120 (4)20 1
5. In the subtraction formula, the difference is 45 of subtraction, and the ratio of subtraction to minuend is ().
( 1) 1:5 (2) 1:9 (3)5:9 (4)4:9
Third, be careful.
1, find the ratio.
02:0.8 2:0.25
12 :56 4: 13
2. Simplify the proportion.
85 :23 0. 14:0.56
12 : 14 2:0.5
3. Solution ratio.
x:: 14 = 6:28 0.75 x = 0.253 38: 13 = x: 16
4. Write the ratio and the solution ratio according to the following conditions.
1, the ratio of 0.2 and 4 is equal to the ratio of x and 20.
2. The two external terms of the ratio are 2 and x, and the two internal terms are 120 and 8.
Fourth, the little designer.
The foundation of Huo Xing primary school teaching building is rectangular, with a length of 40m and a width of15m. Please choose a suitable scale and calculate how many centimeters should be drawn on the map? Draw a plan of the foundation and mark the length and width on the plan.
Fifth, the application is online.
1. The actual distance from Shanghai to Hangzhou is150km. On the map, the distance between the two places is 3 cm. Find out the scale of this map.
2. Xiaohong read story books, and read 72 pages in 6 days. According to this calculation, she studied 15 days. How many pages did she read? (Answer in two ways)
It takes 720 square bricks with a side length of 0.3m to pave a piece of land. If you use a square brick with a side length of 0.4 meters, how many pieces do you need? (Answer with proportional knowledge)
4. The rectangular playground is100m long and 50m wide. Draw on the map with the scale of 12000. How many centimeters should I draw the length and width? Please draw this rectangle.
5. A bamboo pole with a length of 1.5m stands upright on the ground, and its shadow length is1.2m. At the same time, the shadow length of the flagpole of this school is 6.4m How high is the flagpole of this school?
6. There is 300g of salt water with a salt content of 15%. How many kilograms of water do you need to add to reduce the salt content to 5%?
Sixth, challenge yourself.
There is a piece of copper-zinc alloy, and the weight ratio of copper to zinc is 2: 3. If 6 grams of zinc is added, the weight of the new alloy is 36 grams. Find the weight ratio of copper and zinc in new alloy.