1. There are 40 students in a class, of which 15 is in the math group, 18 is in the model airplane group, and 10 is in both groups. So how many people don't participate in both groups? There are forty-five students in a class who took the final exam. After the results were announced, 10 students got full marks in mathematics, 3 students got full marks in mathematics and Chinese, and 29 students got no full marks in both subjects. So how many people got full marks in Chinese? 3.50 students stand in a row facing the teacher. The teacher asked everyone to press 1, 2,3, ..., 49,50 from left to right. Let the students who are calculated as multiples of 4 back off, and then let the students who are calculated as multiples of 6 back off. Q: How many students are facing the teacher now? 4. At the entertainment party, 100 students won lottery tickets with labels of 1 to 100 respectively. The rules for awarding prizes according to the tag number of lottery tickets are as follows: (1) If the tag number is a multiple of 2, issue 2 pencils; (2) If the tag number is a multiple of 3, 3 pencils will be awarded; (3) The tag number is not only a multiple of 2, but also a multiple of 3 to receive the prize repeatedly; (4) All other labels are awarded to 1 pencil. So how many prize pencils will the Recreation Club prepare for this activity? 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 it at the marked place. How many ropes were cut? The fifth grade answered 1, because there were 10 participants in both groups, so only five students participated in mathematics and only eight students participated in the model airplane, plus that 10 was 23 students, and 40-23= 17, 17 people did not participate in both groups. Similarly, math. 45-7-29=9, which is the person with full marks in Chinese (if only full marks in Chinese, you need to subtract 3); 3, 50÷4 is rounded to 12, and 50÷6 is rounded to 8, but it should be noted that the multiple of 4 may be a multiple of 6 at the same time, so to calculate the common multiple of 4 and 6, use 50÷. Should it be 50- 12-8+4=344, 100÷2=50, 100÷3=33 (rounded) or the common multiple of 2 and 3 =100 ÷? It is only necessary that the length and width are several times the diameter of the circle, and then the product of the multiples of the length and width is found. 1m20cm = 120cm120 ÷ 30 = 4 90 ÷ 30 = 34× 3 =12 (block) A: You can cut12 at most. 2. A cylinder with a bottom radius of 1 decimeter has a square profile. What is the surface area and volume of this cylinder? Analysis: Starting from the square of the side expansion diagram, we can know that the height of this cylinder is the circumference of the bottom of the cylinder. Surface area of cylinder: (3.14×12 )× (3.14×12)+3.14×/kloc-0. Volume of cylinder: 3.14×1× (3.14×12) = 3.14× 6.28 =/kloc-0. A train leaves from Station A at 8 a.m. and arrives in bilibili at 9 p.m. the next day. As we all know, the train travels at an average speed of 98 kilometers per hour. How long is the railway between Station A and bilibili? Analysis: The key to solve this problem is to know the time of the train. 24-8+9=25 (hours) [or: 12-8+ 12+9=25 (hours)] 98× 25 = (100-2 )× 25 = 2500-50. The circle and the sector have the same radius. It is known that the area of a circle is 30 square centimeters and the central angle of a sector is 72 degrees. Find the area of the sector. Analysis: Because the radii of a circle and a sector are equal, the area of a circle and a sector should be multiple. This multiple is the multiple relationship between their central angles. 72÷360= 1/5, 30× 1/5=6 (square centimeters) A: The area of the sector is 6 square centimeters. Question 1 1: Draw a sector in a circle with a radius of 3 cm so that its area accounts for 20% of the area of the circle, and calculate the area of this sector. Analysis: This question is the same as the above question. 3. 14×3×3×20%=5.652 (cm2) A: The area of this sector is 5.652 cm2. 5. The school divided the task of planting trees into 6 levels and 5 levels according to 5: 3. The sixth grade actually planted 108 trees, exceeding the original task by 20%. How many trees were planned to be planted in the fifth grade? Analysis: The number of trees planned for the sixth grade is the key to solve the problem. /kloc-How many trees were originally planned to be planted at Grade 0 and Grade 6? 108 ÷ (1+20%) =108× 5/6 = 90 (tree) 2. How many trees were planned to be planted in the fifth grade? 90÷5×3=54 (plants) Comprehensive formula:108 ÷ (1+20%) ÷ 5× 3 = 90 ÷ 5× 3 = 54 (plants) Answer: 54 plants were originally planned for grade five. 6. Two engineering teams, Party A and Party B, completed a section of the road, and the working efficiency of Team A was three-fifths of that of Team B. Two teams completed two-thirds of the road in six days, and the rest was repaired by Team B alone. How many days will it take to finish it? Analysis: Finding the working efficiency of two teams is the key to solving the problem. 1. What is the sum of the work efficiency of the two teams? 2/3 ÷ 6 =1/92. What is the working efficiency of team B? 1/9× [5 ÷ (3+5)] =1/9× 5/8 = 5/723, how many days will it take to complete? (1-2/3) ÷ 5/72 =1/3× 72/5 = 24/5 (days) A: It will take another 24/5 days to finish. 7. A cement factory produced 232,400 tons of cement last year. The output in the first five months of this year is equal to that in the whole of last year. According to this calculation, the output of this cement plant will increase by a few percent this year compared with last year. Scheme 1: The analysis shows that the output will increase in the last seven months of this year, so we have to calculate the output in the last seven months first. 232400 ÷ 5× (12-5) = 46480× 7 = 325360 (ton) 325360÷232400= 1, 4= 140% solution 2: amplification. 1÷5= 1/52. How much has the output increased this year compared with last year? 1/5×( 12-5)=7/53. Compared with last year, what percentage has the output increased this year? 7/5= 1.4= 140% Comprehensive formula:1÷ 5× (12-5) =1.4 =140% Answer: 8. The kindergarten bought 40 towels of different sizes, which cost 258.8 yuan. The unit price of a large towel is twice that of a small towel, with a difference of 0. 1 1 yuan. What is the unit price of these two kinds of towels? Solution: If the unit price of a small towel is X yuan, then the unit price of a large towel is (2x+0. 1 1) yuan. [x+(2x+0. 1 1)]×40 = 258.83 x = 6.47-0. 1x = 6.36÷3x = 2. 122 x+0.65438+。 9. A room with a length of 4-8m and a width of 3-6m needs 768 square bricks with a side length of 0,15m. A room 6 meters long and 4 or 8 meters wide, how many tiles do you need if you use the same tiles? How many square bricks with a side length of 0 or 2 meters should be used in the first room? Analysis: The area of the room is fixed, and the area of each brick is inversely proportional to the number of blocks. Solution: Suppose X blocks are needed. 0.15× 0.15x = 6× 4.8x = 6× 4.8 ÷ 0.15 ÷ 0.15x =1280a: required/. Solution: suppose you need y blocks. 0.2× 0.2y = 4.8× 3.6y = 4.8× 3.6 ÷ 0.2 ÷ 0.2y = 432a: 432 pieces are needed. 10. Shipborne diesel can be used for up to 6 hours. When driving out, it was downwind, with a speed of 30 kilometers per hour. When driving back against the wind, the distance per hour is 4/5 of that when driving with the wind. How far should the ship sail before returning? Analysis: The distance traveled by a ship is constant, and the distance traveled per hour is inversely proportional to time. Solution: Suppose the ship sailed against the wind for x hours. 30× 4/5x = 30× (6-x) 4/5x = 6-x9/5x = 6x =10/330× 4/5x10/3 = 80 (km) A: It is time for this ship to sail back. 1 1. A car traveled from place A to place B in the first hour 1/7, and the second hour traveled more than the first hour 16 km. At this time, it is 94 kilometers away from B. How many kilometers is the expressway between A and B? Analysis: "The second hour is longer than the first hour 16km", which means that the second hour is 1/7, 16km. The first hour and the second hour * * * are (1/7+ 1/7) and 16 km respectively. It can be seen that (96+ 16) accounts for the whole process (1- 1/7- 1/7). According to the above analysis, it is: (96+16) ÷ (1-kloc-0//7) =112 ÷ 5/7 =168. Or solve it by equation: Solution: Let the expressway between A and B be x kilometers long. (1-1/7-1/7) x = 96+165/7x =12x =156,8 a:. Topic adaptation: If one of the conditions in this question is changed to "96 kilometers away from a certain place at this time", other conditions will remain unchanged and the problem will remain unchanged. How to answer? 12. A knitting group originally produced 1500 flower baskets for 30 people 10 day. Now it has increased to 80 people. According to the original work efficiency, how many days does it take to produce 6000 flower baskets? Analysis: the title says "according to the original working efficiency", which shows that the working efficiency of this textile group is certain. The work efficiency is certain, and the total amount of work is directly proportional to the working hours. Solution: Suppose it takes X days. 1500:(30×50)= 6000:(80×x) 1500×(80×x)= 6000×(30×50)x = 6000×30×50÷80÷。

It's finally done, okay? From my mystery book.