Seventh grade math questions

1. In order to save energy, a certain unit charges monthly electricity bills according to the following regulations: if the electricity consumption does not exceed 140 kilowatt hours, it will be charged at 0.43 yuan per kilowatt hour; if it exceeds 140 kilowatt hours, the excess will be charged at 0.57 yuan per kilowatt hour. . If the electricity bill for electricity users in Mexico in April averages 0.5 yuan per kilowatt hour, how much yuan should the electricity user pay for electricity in April?

2.1) The ratio of delivery personnel to sales personnel in the home appliance department of a large shopping mall is 1:8. This summer, as the purchase volume of home appliances increased significantly, the manager of the home appliance department deployed 22 people from the sales staff to deliver goods. As a result, the ratio of delivery personnel to sales personnel is 2:5. How many delivery personnel and sales personnel are there in the home appliance department of this shopping mall?

2) The price of a certain product is now reduced by 10%. In order to keep the sales amount unchanged, by what percentage should the sales volume increase compared to when it is sold at the original price?

3. A. The sum of the original unit prices of two commodities B is 100 yuan. Due to market changes, the price of commodity A is reduced by 10%, and the price of commodity B is increased by 5%. After the price adjustment, the sum of the unit prices of the two commodities is 2% higher than the sum of the original unit prices. A. What is the original unit price of the two commodities of B/

4. The number of people in workshop A is 30 less than 4/5 of the number of people in workshop B. If 10 people are transferred from workshop B to workshop A, then the number of people in workshop A will be That is 3/4 of workshop B. Find the original number of people in each workshop.

5. A rides a bicycle from A to B, and B rides a bicycle from B to A. Both of them are moving at the same speed, so that they start at the same time at 8 a.m. and arrive at 10 a.m. At that time, the two people were still 36 kilometers apart. At 12 noon, the two people were 36 kilometers apart again. Find A. The distance between two places B? (Series of equations)

6.. The lengths of two trains A and B are both 180 meters. If the two trains are running opposite each other, it will take ***12 seconds from the time the front of the train meets to the time when the rear of the train separates; if they run in the same direction, from When the front of car A meets the rear of car B, it will take 60 seconds until the rear of car A passes the front of car B. The speed of the cars remains unchanged. Find the speeds of cars A and B.

7. Two candles of the same length, the thick one can burn for 3 hours, and the thin one can burn for 8/3 hours. When there is a power outage, light both candles at the same time. When the power comes, blow them out at the same time. The thick one is the thin one. 2 times the length, find the power outage time.

8. A middle school organized a spring outing for first-grade students. It was originally planned to rent a number of 45-seat buses, but there were no seats for 15 people; if the same number of 60-seat buses were rented, If there are 100,000-seat passenger cars, there will be one more car, and the remaining passenger cars will be exactly full. How many people are there in the first grade of junior high school? How many 45-seater buses were originally planned to be rented?

9. Input a batch of accounting statements into the computer. A alone takes 20 hours to complete, while B alone takes 12 hours to complete. Now, A will do 4 hours alone, and the remaining part will be completed by A and B working together. How long will it take for A and B to cooperate?

10. The sum of the three numbers A, B and C is 53, so we know that the ratio of A’s number to B’s number is 4:3, C’s number is 2 less than B’s number, B’s number is (), C’s number is ()

11. The lengths of thick candles and thin candles are the same. The thick candle can burn for 5 hours, and the thin candle can burn for 4 hours. After a power outage, the two candles are lit at the same time, and they are extinguished at the same time after the call comes. It is found that the thick candle can burn for 5 hours. The length of the candle is 4 times the length of the thin candle. How long will the power outage last?

12. For a three-digit number, the number in the hundreds place is 1 greater than the number in the tens place, and the number in the ones place is 2 less than 3 times the number in the tens place. If the three numbers are After the order is reversed, the sum of the obtained three-digit number and the original three-digit number is 1171. Find this three-digit number.

13. Three first-grade classes donated books to Hope Primary School, and one class won 152 The number of books donated by the second class is the average of the three classes. The number of books donated by the third class is 40% of the total number of books donated by the grade. How many books did the three classes *** donate?

14.a b The distance between the two places is 31 kilometers. One hour after A rides a bicycle from place A to place B, B rides a motorcycle and also goes from place a to place b. It is known that A travels 12 kilometers per hour and B travels 28 kilometers per hour. After B sets off, How many hours does it take to catch up with A

15. The load capacity of a cargo ship is 400t and the volume is 860m^3. Now it needs to carry two kinds of cargo: pig iron and cotton. The volume of pig iron per ton is 0.3m^3, and the volume of cotton is 0.3m^3. The volume per ton is 4m^3. How many tons of pig iron and cotton can be loaded to fully utilize the load capacity and volume of the ship?

16. A computer company sells two brands of computers, A and B. The year before last *** 2,200 units were sold. Last year, the number of type A computers sold was 6% more than the year before. The number of type B computers sold was 5% less than the previous year. The total sales of the two types of computers increased by 110 units.

How many computers of A and B were sold in the year before last?

17. The surface area of ??the earth is approximately 71/29 times the land area. The surface area of ??the earth is approximately equal to 510 million square kilometers. What is the land area of ??the earth? (Accurate to 100 million square kilometers)

18. A long cylindrical glass (filled with water) with an inner diameter of 90 mm points toward a ground surface with a diameter of 131*131 mm2 and an inner height of 81 mm. When the iron box is filled with water, how much does the height of the water in the glass drop?

19. A cylindrical glass with an inner diameter of 120 mm and a cylindrical glass dish with an inner diameter of 300 mm and an inner height of 32 mm can hold the same amount of water. What is the inner height of the glass?

20. Pour the full bucket of water from a cylindrical bucket with an inner diameter of 200 mm into a rectangular iron box with an inner length, width, and height of 300 mm, 300 mm, and 80 mm respectively, until it is exactly full. . Find the height of the water in a cylindrical bucket? (Accurate to millimeters. π is taken as 3.14)

21. There is a cylindrical oil reservoir with a bottom radius of 5cm. There are iron balls embedded in the oil. If an iron ball weighing 546π grams is fished out, How many centimeters will the liquid level drop? (An iron ball of 1 cubic centimeter weighs 7.8 grams)

22. If the root of the equation X+3=X+1 is greater than the equation about X, a/4(x+2)-2 1/2 = the opposite of the root of a/2 is greater than 2. Try to discuss the equation 1/2/a of Lottery, after walking 450 meters, grandma found that grandpa forgot to bring something. If grandma goes to deliver it immediately, it will take her 15 minutes to catch up with grandpa. If grandpa finds out and returns home immediately, they can meet in 3 minutes. Please grandpa, How many meters does grandma walk per minute?

24. There are some cards marked with 6, 12, 18, 24... (the latter one is 6 larger than the previous one). Li Bing took three adjacent cards. After calculation, their sum is 1998

(1) Do you know which three cards he took?

(2) If you are asked to take 3 adjacent cards, can you make their sum equal to 2008?

25. There is a two-digit number that is 161 smaller than a three-digit number. Write the two-digit number to the right of the three-digit number to get the five-digit ratio. Write the three-digit number after the two-digit number. The obtained five-digit number is 6561. Find this three-digit number and this two-digit number

26. A factory produces a kind of mechanical parts with a fixed cost of 20,000 yuan and a cost of each part of 3 yuan. , the retail price is 5 yuan, and the tax payable is 10% of the total sales. If the factory is to be profitable, it must produce and sell at least X units of this part. Try to write the inequality that X should satisfy

27. The survey results show that individual clothing sellers can make a profit as long as they sell at a price that is 20% higher than the purchase price, but the boss often sets a price that is 50% to 100% higher than the purchase price. If you are going to buy a piece of clothing with a price of 200 yuan, Clothing, within what range should I counter-offer?

28. Ship A goes down the river from Pier A, and ship B goes upstream from Pier B. The two ships move towards each other at the same time and meet at the midpoint. The speed of ship B sailing downstream is A The speed of the ship sailing against the current is 2 times. It is known that the water speed is 4km per hour. Find the speed of the two ships in still water

29. The lengths of the two heights of scalene triangle ABC are 4 and 12. If the length of the third height is an odd number, try to find the length of the third height

30. The distance between A and B is 360 kilometers. Car A starts from A to B. , the speed is 72 kilometers per hour. 25 minutes after car A sets off, car B sets off from point B to point A. The speed is 48 kilometers per hour. How long does it take for car A to set off? Are the two cars 100 kilometers apart? (Answer in two situations)

31. If a piece of iron wire is surrounded by a rectangle, its length can be 2 cm longer than its width. If it is surrounded by a square, the side length is exactly 5 cm. Find the enclosed area. What are the length and width of the rectangle in centimeters?

32. The long side of a rectangular chicken farm is against a wall, the wall is 14 meters long, and the other three sides are surrounded by bamboo fences. The existing bamboo fence is 35 meters long. Xiao Wang plans to use it to surround a chicken farm, with the length being 5 meters longer than the width. Xiao Zhao also plans to use it to surround a chicken farm, with the length being 2 meters longer than the width. . Whose design do you think is realistic? According to his design, what is the area of ??the chicken farm?

33. There is a TV in a shopping mall. The original price of each set is 2,500 yuan, and it is now sold at a 20% discount. If you want the sales before and after the price reduction to be 100,000 yuan, how much should the sales increase? ?

34. Xinhua Bookstore sells two kinds of books in one day, and the first type of book A sells for 1,560 yuan.

In order to develop agricultural science and technology, books of type B were sent to the countryside and sold for 1,350 yuan. If the costs of books A and B are calculated separately, book A makes a profit of 25% and book B loses 10%. How about this day of the bookstore* **How ??much is the profit (or loss)?

35. A bookstore marked a pair of trousers at a 50% increase in cost and sold them at a 20% discount. As a result, each pair of trousers made a profit of 10 yuan. How much does this pair of trousers cost?

36. The manager of the shoe and hat department of a shopping mall asked the salesman Xiao Wang to set a price for a newly arrived batch of leather shoes. He said: "The purchase price of each pair of these shoes is 200 yuan, and we will price it according to the price of 8 Sold at a discount, with a profit margin of 20%." Can you help Xiao Wang determine the price of each pair of leather shoes?

37. A company produces a product with a cost price of 400 yuan per piece and a sales price of 510 yuan. It sold 1,000 pieces this quarter. In order to further expand the market, the company decided to lower the sales price. At the same time reduce production costs. After market research, it is predicted that the sales price of each piece of this product will decrease by 4% in the next quarter, and sales volume will increase by 10%. To keep the sales profit constant, by how much should the cost price of each unit of this product be reduced?

38. A store mixes two candies with prices of 28 yuan per kilogram and 20 yuan per kilogram into mixed candies for sale. Now it is necessary to prepare 100 kilograms of this mixed candies and make its selling price For 25 yuan per kilogram, how many kilograms of each of these two candies are needed?

39. A school has an existing school building of 20,000 square meters. It plans to demolish part of the old school building and build a new school building. The area of ??the new school building is 2,000 square meters more than four times the demolished area. If the total area of ??the school building after construction is to be increased by 40% compared to the existing school building area, how many old school buildings will be demolished and how many new school buildings will be built?

40． There is a ship with a load capacity of 800 tons and a volume of 750 cubic meters. Now it needs to transport pig iron and cotton. The volume of pig iron is 0.3 cubic meters per ton and the volume of cotton is 4 cubic meters per ton. Please help the captain design it. , how to ship to make full use of the ship's load capacity and volume?

41. A certain city charges monthly gas fees according to the following regulations: if the gas consumption does not exceed 60 cubic meters, it is charged at 0.8 yuan per cubic meter. If the gas consumption exceeds 60 cubic meters, the excess is charged at 1.2 yuan per cubic meter. It is known that a user 10 The average monthly gas fee is 0.88 yuan per cubic meter. Find the gas fee payable by this user in October.

42. A train moving at a constant speed passed through a 300-meter-long tunnel in 15 seconds (that is, from the time when the front of the car entered the tunnel to when the rear of the car left the tunnel). We also know that a beam of light from a fixed light at the top of the tunnel illuminates the train vertically for 2.5 seconds.

1) Find the length of the train

2) If the train The train passed through another tunnel in 25 seconds. Find the length of this tunnel

43. Xiaobin and Xiaoming insist on running every morning. Xiaobin runs 4 meters per second and Xiaoming runs 6 meters per second. (1) If they stand at both ends of a 100-meter track and start running towards each other at the same time, how many seconds will it take for them to meet? (2) If Xiao Ming stands at the starting point of the 100-meter track and Xiao Bin stands 10 meters in front of him, and they both start running in the same direction at the same time, how many seconds will it take for Xiao Ming to catch up with Xiao Bin?

44. A cycling team is training. During the training, all team members are moving at a speed of 35 kilometers/hour. Suddenly, member No. 1 is walking alone at a speed of 45 kilometers/hour and travels 10 kilometers. Then he turned around and rode back at a speed of 45 kilometers per hour until he met up with other team members. How long did it take for Team 1 to rejoin the other team members?

45. National regulations: "From November 1, 1999, interest tax will be levied on savings deposits nationwide, and the interest tax rate is 20%." Teacher Wang transferred 10,000 yuan to If deposited in a bank, the annual interest rate is 2.25%. What is the sum of principal and interest he will receive after one year of depositing?

46. Xiaobin deposited a sum of New Year's money into the "Children's Bank" on a regular basis for one year, with an annual interest rate of 10%. After maturity, he will withdraw the principal and interest and donate 50 yuan of it to "Children's Bank". "Project Hope", and the rest is all deposited regularly for one year. This means that the annual interest rate of the deposit has been reduced to half of the annual interest rate of the last deposit. In this way, after maturity, you can get the principal and interest of 63 yuan. You Can you calculate how much Xiaobin’s new year’s money is?

47. The anti-smuggling boat and the smuggling boat are 42 nautical miles apart. If the smuggling boat continues to move forward and the anti-smuggling boat goes to search, they will meet in 2 hours. If the smuggling boat escapes in the opposite direction, the anti-smuggling boat will take 14 hours to escape. In order to catch up, what are the speeds of the anti-smuggling boat and the smuggling boat?

48. A person takes a boat from point A to point B, and then upstream to point C. It takes 4 hours. It is known that the speed of the boat in still water is every 7 .

7.5 kilometers per hour, the speed of the water flow is 2.5 kilometers per hour, if the distance between AC and AB is 10 kilometers, what is the distance between AB and AB?

49. There is currently 400g of salt water containing 15% salt. Teacher Zhang requested that the salt water concentration be changed to 12%. A certain student added 110g of water after calculation. Please verify that the student added 110g of water by solving the equation. Is the correct amount of water entering?

50. A certain national ministry has three agencies A, B, and C. The civil servants in these three agencies are 88, 52, and 60 in order. In this year’s institutional reform, the three agencies are required to The same proportion of layoffs will leave 150 civil servants in the three agencies. Then how many people will be laid off in agency C?

51. Copy a material. If you copy 30 words per minute, then It can be copied in a few hours. When the copying reaches 2\5, due to the change of method, the work efficiency is increased by 40%. As a result, the copying is completed half an hour earlier. How many words does this material have?

52. The sum of the ages of A and B this year is 63. When A’s age is half of B’s current age, B is exactly A’s current age. How old are A and B each this year?

53. Patrol cars travel 200 kilometers per day, and each patrol car can carry gasoline for 14 days of driving. There are currently 5 patrol cars, starting from point A at the same time. In order to allow three of the vehicles to patrol as far away as possible (and then return together), after the two vehicles A and B arrive at point B, they only have enough gasoline to return to the base. , supply the excess gasoline to other cars, and ask what is the furthest distance traveled by the other three cars?

54. Two people, A and B, are running on a 400-meter-long circular track. A’s speed is 360 meters/min, and B’s speed is 240 meters/min.

1) Two People run in the same place and in the same direction at the same time. How long did it take for the two people to meet for the first time? How many laps did they run at this time?

2) Two people run in opposite directions at the same time. How long did it take for them to meet for the first time?

3) Two people run in the same place and in the same direction. A runs first for 30 seconds. How long will it take for them to meet for the first time?

4) Two people run in the same place and in the same direction. If B runs first for 30 seconds, how long will it take for them to meet for the first time?

55. On Sunday, my mother went to my grandma’s house. After walking for an hour, Xiao Ming found that I didn’t bring the gift for my grandma, so he immediately took the gift and rode a bicycle to chase after it. The cute little flower dog also ran away. , after it caught up with his mother, he immediately returned to Xiao Ming, and then returned to chase his mother. He kept running back and forth between his mother and Xiao Ming until Xiao Ming caught up with his mother. If his mother walked 4 kilometers per hour , Xiao Ming walks 12 kilometers per hour, and the speed of the little flower dog is 16 kilometers. Can you calculate how many kilometers the little flower dog ran in one hour when Xiao Ming caught up with his mother?

56. During the May Day holiday, a principal took five outstanding student leaders on a trip. Travel agency A said: "If the principal buys a ticket, the students can all enjoy a half-price discount"; travel agency B said: "Everyone, including the principal, is discounted by 60% of the original price." The principal asked the students to calculate, and found out that they could save 24 yuan by buying tickets from travel agency A, and asked for the price of one ticket.

57. There was a square green space. First carry out the following transformation, reduce the length by 2 cm and increase the width by 2 cm. After the transformation, a square green space will be obtained. Its area is twice the area of ??the original green space. What is the area of ??the square green space after the transformation?

58. A document needs to be printed. It takes 6 hours for Xiao Li to complete it alone, and 8 hours for Xiao Wang to complete it alone. If two people do it at the same time, how long will it take to complete it?

59. One day, Descartes lit two candles to read. The two candles were the same length but different in thickness. It is known that the thick candle can be lit for 5 hours and the thin candle can be lit for 4 hours. Before going to bed, When the candle is blown out, the length of the remaining candle is exactly 4 times that of the thin candle. How long have these two candles been lit?

60. The state stipulates that the tax calculation method for the royalties received by individuals for publishing articles and books is (1) no tax is paid if the royalties are not more than 800 yuan; (2) the royalties are more than 800 yuan but not more than 4,000 yuan Those whose royalties exceed 800 yuan should pay a tax of 14% on the portion of the royalties; (3) those whose royalties exceed 4,000 yuan should pay a tax of 11% of the entire royalties.

Teacher Jin Ding received a manuscript fee and paid a personal income tax of 420 yuan. I asked Teacher Ding how much the manuscript fee was.