2. The inner bottom area of the water tank is 300 square centimeters and the height is 20 centimeters. Now put a cubic lead block with a side length of 10cm, and then fill it with water. How deep is the water in the tank when the lead block is taken out of the tank?
There are 4000 chickens in the chicken farm, among which there are 500 fewer broilers than laying hens. How many broilers and laying hens are raised respectively?
Lao Wang, a carpenter, needs two drawers to make a writing desk. The drawer is 8dm long, 6dm wide and 1dm high. It is estimated that a 4 mm2 plate will suffer losses in the manufacturing process. How many boards should Lao Wang prepare at least?
5. I bought 20 pencils of 0.50 yuan and 0.80 yuan in winter and winter, and spent 12.40 yuan. How many pencils did you each buy?
1. Use a line with a length of 3 14 cm to form the largest circle. What is the radius of this circle? If you enclose it in a square, what is the area of the square?
2. A rope with a length of 13.26 meters can circle the trunk four times, leaving 0.7 meters. What is the cross-sectional diameter of the trunk of this tree?
The radius of a circle is 2 meters, the length of a rectangle is equal to the circumference of the circle, and the width is equal to the diameter of the circle. How many square meters is the area of this rectangle?
4. The wheel diameter of the car is 8 cm, and the wheel rotates 100 times in the first minute. How many minutes does it take to cross a bridge 25 12 meters long?
5. Uncle Li enclosed a semi-circular chicken farm with a fence of 12.56 meters. What is the area of this chicken farm?
6. Xiaoming tied a sheep to a stake on the rectangular grass. If the rope that binds the sheep is 4 meters long, what is the area of grass that the sheep can't eat?
7. The picture shows a rectangle 6.28 cm long. Its area is equal to that of a circle. What is the area of this circle?
1). Divide 20 pears and 25 apples among the children. After the division, there are 2 pears left and 2 apples missing. There are _ _ _ _ children in a * *.
2) There are natural numbers whose plus 1 is a multiple of 2, plus 2 is a multiple of 3, plus 3 is a multiple of 4, plus 4 is a multiple of 5, plus 5 is a multiple of 6, and plus 6 is a multiple of 7. The smallest of these natural numbers except 1 is _ _.
3), using 0, 1, 2, 3, 4 can form at least () non-repetitive three digits.
4) There are 40 students in one class, including math group 15 and model airplane group 18, both of which are 10. Then there are () people who don't participate in both groups.
5) There is a rope with a length of 180 cm. Make a mark every 3 cm and 4 cm from one end, and then cut off the marked place. The rope was cut into () sections.
6) The sum of numbers A and B is 8.5. If the decimal point of a number is shifted to the right by one place, it is exactly seven times that of b number, and b number is ().
7) The fourth decimal place of the quotient of 50 divided by 7 is (), and the thirtieth decimal place is ().
8), rectangle, if the height increases by 2cm, it becomes a square. At this time, the surface area increased by 56 square decimeters, and the original cuboid volume was ().
9) The surface area of a cuboid is 3 14 square decimeter, the bottom area is 72 square decimeter, the bottom circumference is 34 decimeter, and the volume is () cubic decimeter.
10), the surface area of the cubic fish tank is 259.2 square decimeter, and the volume is () cubic decimeter.
1 1), the surface areas of cubes and cuboids are reduced by 50 square decimeters, and the original surface area of cubes is () square decimeters.
12), the areas of three sides of a cuboid are 10 square decimeter, 15 square decimeter and 6 square decimeter respectively, so the volume of this cuboid is () cubic decimeter.
13), the known number A =2×a×3×7, the number B =2×3×b×5× 1 1, and A and B are coprime, and a≠b≠0 is the greatest common divisor of A and B.
14), two four-digit numbers A275 and 275B are multiplied so that their product energy can be divisible by 72. A is () and b is ().
15), there are 16 bottles of wine, one of which is weak. If you weigh it at least () times, you can find it.
16), a box of eggs sold half for the first time, the remaining half for the second time, the remaining half for the third time and the remaining half for the fourth time. Finally, there are three eggs left in the box. There are () eggs in this box.
Second, solve the problem (7 points per question)
17), as shown in the figure, quadrilateral AB= 8cm CD=2cm, what is the area of quadrilateral ABCD?
18) In order to estimate the number of fish in the pond, 1000 fish were caught from the pond, marked and put back into the pond. After a while, the marked fish and the fish were completely mixed together, and 200 more were caught. If there are 10 fish, how many fish are there in the pond?
19) There is a two-digit number divided by 8 plus 1, divided by 5 plus 2, divided by 7 plus 6, so what is this number?
20) Party A and Party B walk opposite AB, meet at a distance of 600 meters from B, walk again, return to BA, and meet at a distance of 300 meters for the second time. What's the distance between AB and B?
2 1) the car delivers goods to the mountain area, with a speed of 40 kilometers per hour when going uphill and 60 kilometers per hour when turning back. What is the round-trip speed of this car?
22) A cubic container is 8 centimetres long from the inside and contains some water. Now use a ruler with a length of 100 cm, a width of 1 cm and a thickness of 0.2 cm to measure that the water surface is 3 minutes away from the upper end of the container. Now, put a stone in it, then put the ruler in the water, show the scale of 6.5 decimeters, and find the volume of this stone.
23) Punch a hole with a side length of 2 cm in the center of six faces of a cube with a side length of 10 cm, and calculate the surface area and volume of the rest.