2. The length of a rectangle is fixed, and the area and width are in (positive) proportion. The area of a rectangle is constant, and its length and width are inversely proportional.
3. The circumference of the bottom of a cylinder is 12.56 cm and the height is 6 cm, so the radius of the bottom is (2) cm, the area of the bottom is (12.56) cm 2, and the area of the side is (75.36) cm 2.
I bought some fruits in the school canteen. The unit price and quantity of fruits are as follows: As can be seen from the table, the fruit with less (unit price) will buy more, while the fruit with more (unit price) will buy less. The product of (unit price) and (quantity) is certain, so (unit price) and (quantity) are inversely proportional.
The ratio of 5.800: 1 means that the distance on the map is (1/800) times the actual distance.
6. The side area of a cylinder is constant, and the perimeter of its bottom is inversely proportional to its height.
7. The sum of the volumes of cylinders and cones with equal bottoms and equal heights is 72 cubic decimeters, the volume of cylinders is (54 cubic meters), and the volume of cones is (18 cubic meters).
8. The circumference of the cone bottom is 12.56 cm and the height is 8 cm. The surface area is increased by (16) cm 2 when it is cut into two equal halves along the height from the vertex.
9. The sum of number A and number B is 63, the ratio of number A to number B is 2:7, number A is (14) and number B is (49).
Second, the judgment (4 points)
1, expand the actual length by 400 times and draw it on the drawing. The ratio is 400: 1. (√)
2. The diameter of the bottom of the cylinder is 2 cm and the height is 6.28 cm. Its side is a square when it is unfolded. (√)
3. The total amount of water is fixed, and the tonnage of water used is inversely proportional to the remaining water. (×)
4. Cubes and cylinders have the same bottom area and height, and their volumes must be the same. (√)
Three. Choice (4 points)
1, a cylindrical plasticine can be kneaded into (c) conical plasticine with the same bottom and the same height. a、 1 B、2 C、3 D、4
2. If A = B ÷5, then A and B (a). A, proportional to B, inversely proportional to C, out of proportion
3. The area of a rectangle is12cm2, and its area is (c) after being enlarged according to the ratio of 1:4. A, 48cm2 b, 96cm2 c,192cm2
4, the following life phenomenon, belongs to the phenomenon of narrowing is (c). A, read a book with a magnifying glass B, look at cells C with a microscope, and take pictures with a camera
Four, calculation (20 points)
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Five, solve the problem (34 points)
1. The school library wants to buy some books. The quantity and total price of The Story King are as follows: (14) (1) Fill in the above table completely. (2) According to the data in the table, draw the points corresponding to the number of copies and the total price in the figure below, and then connect these points in turn. (3) Is the total price of Story King proportional to the number of copies? Why? (4) As can be seen from the picture, it costs () yuan to buy four copies of Story King; 72 yuan can buy the king of stories.
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2. In order to respond to the government's call for "green homeland and harmonious construction", Licun will dig a cylindrical biogas digester with a bottom radius of 5 meters and a depth of 2 meters. Cement is laid on the side and bottom of the biogas digester. What is the area of cement?
Bottom area: 3. 14*5? =78.5
Side area: 3. 14*(5*2)*2=62.8.
Required area: 78.5+62.8 =141.3m2.
How far is Xiaoming's home from the stadium? (in centimeters)
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