(1) Travel issues:

1. From place A to place B, it takes someone 3.6 hours longer to walk than to take a bus. It is known that the walking speed is 8 kilometers per hour and the bus speed is 40 kilometers per hour. If the distance between A and B is X kilometers, the equation is _ _ _ _ _ _ _ _ _.

2. Party A and Party B set out at the same time at a distance of 18km, face to face, and meet at 1 hour 48. If Party A starts 40 minutes earlier than Party B, then they will meet at a distance of 30 minutes from Party B 1 hour, and seek the speed of both parties. ..

3.？ Someone rides a bike from home to school. If you drive at a speed of 15 km/h, you can arrive 15 minutes earlier than the scheduled time; If you drive 9 kilometers per hour, you can arrive 15 minutes later than the scheduled time; How many kilometers is the distance from home to school?

On the 4.800-meter runway, two people are practicing middle and long distance running. A runs 320 meters per minute, and B runs 280 meters per minute. Both of them set out at the same time, place and direction, and met for the first time after t minutes. T equals? Minutes.

5. How long is a bus? M, a freight train is 280 meters long? M, reverse driving on parallel tracks. It takes 16 seconds from the time when two cars meet to the time when two cars leave each other. As we all know, the speed ratio of passenger cars to trucks is 3: 2. How many meters do two cars travel per second?

On a road parallel to the railway, a group of people and cyclists are driving south at the same time. Pedestrian speed is 3.6Km per hour, and cyclist speed is 10.8Km per hour. If a train comes from behind them, it takes 22 seconds to overtake pedestrians and 26 seconds to overtake cyclists.

(1) What is the speed of pedestrians per second? Find out the length of this train in meters.

7. On the rest day, my mother and I set out from home to my grandmother's house. After we left 1 hour, my father found that he had left a gift for his grandmother at home, so he immediately took the gift and chased it at a speed of 6 kilometers per hour. If my mother and I walk 2 kilometers every hour, it will take 1 hour and 45 minutes to get from home to grandma's house. Before my mother and I go to my grandmother's house, ask my father if he can catch up with us.

8. On an outing, someone walked and someone took a bus, and both of them set off at the same place. The speed of the car is 60 km/h, our speed is 5 km/h, and pedestrians start earlier than the car 1 hour. After the car arrives at the destination, pick up the pedestrians behind. The distance from the starting point to the end point is 60 kilometers. Q: How long does it take for pedestrians to meet the car that will pick them up later?

The time for the car to turn around is negligible?

Clock problem:

/kloc-When does the minute hand and the hour hand coincide between 0/0.6 and 7 o'clock? (textbook review questions)

Navigation problems:

12.？ A ship is sailing between two docks. The current speed is 3 kilometers per hour. It takes 2 hours to sail downstream and 3 hours to sail upstream. What's the distance between the two docks?

13. An airplane flies between two cities with the wind speed of 24 kilometers per hour. It takes 2 hours and 50 minutes to fly with the wind and 3 hours to fly against the wind. Find out the distance between the two cities.

(2) Engineering problems:

1. For a project, it takes 10 days for Party A to do it alone, and 15 days for Party B to do it alone. Four days of cooperation, how many days does the remaining Party B need?

2. A project is completed by two teams, Team A and Team B. It takes 16 days for Team A to complete it alone, and 12 days for Team B to complete it alone. If Team A works for four days first, and then two teams work together, how many days will it take to complete 5/6 of the project?

As we all know, the pool has a water inlet pipe and a water outlet pipe. The water inlet pipe can fill the empty pool 15 hours, and the water outlet pipe can fill the pool for 24 hours.

(1) How much water can be injected per hour if the water inlet pipe is opened separately?

(2) If the outlet pipe is opened separately, how much water can be released per hour?

(3) If two pipes are opened at the same time, what is the effect per hour? How to form?

(4) For an empty pool, if the water inlet pipe is opened for 2 hours first, and then the two pipes are opened at the same time, how long will it take to fill the pool?

There is a pool filled with two water pipes. If the nail pipe is opened separately, the pool will be filled in 2 hours and 30 minutes; If opened separately, the pool will be filled.

B tube, 5 hours to fill the pool.

①? If pipe A and pipe B are injected with water for 20 minutes at the same time, then pipe B is injected with water separately. Ask how long it will take.

The pool is full?

②? Assuming that a drain pipe C is installed under the pool, a pool can be filled with water after opening the pipe C for 3 hours. If three

How many hours does it take to fill an empty pool with water when the pipes are open at the same time?

(3) the difference with the times (production, work and other issues):

1. It takes 40 hours for one person to sort out a batch of books. Now it is planned that some people will work for four hours first, and then two people will work with them for eight hours to finish the work. Assuming that these people are equally efficient, how many people should be arranged to work first.

2. What is the price of water, electricity and gas in a residential area in Yuechi County? Water per ton 1.55 yuan. 0.67 yuan per kilowatt hour. Natural gas per cubic meter 1.47 yuan. A resident paid RMB 67.54 in June 2006 +065438+ 10. This includes the cost of using 5 tons of water, 35 kWh of electricity and some natural gas. It also includes the service fee of 4.00 yuan paid to the property management. How many cubic meters of natural gas did residents use in June, 2006, 5438+065438+ 10?

3. It is known that the taxi charging standard in our city is as follows: 2 yuan is charged if the mileage does not exceed 2 kilometers; If the mileage exceeds 2 kilometers, the excess part will be charged at 1.4 yuan per kilometer except 2 yuan.

(1) If someone drives a taxi for x kilometers (x >: 2), how much should he pay? (column algebra, no simplification) (8 points)

(2) A tourist takes a taxi from the passenger center to Sanxingdui and pays the fare 10.4 yuan. Try to estimate how many kilometers it is from the passenger center to Sanxingdui.

4. A workshop processes 30 parts. If a worker does it alone, he can finish the task as planned, while if B worker does it alone, he can finish the task one and a half days ahead of schedule. It is known that worker B makes 1 parts more than worker A every day. How many parts can a worker make every day? How many days was originally planned to be completed?

It is known that 5 yuan is more expensive to buy a goods than b goods. Someone used 300 yuan to buy item A and several items B of 10. At this time, the total number of products A and B is five more than the number of products A purchased with all this money. How much are goods A and B respectively?

According to the plan, two shift workers should produce 680 parts this month. In fact, the first group completed 20% of this month's tasks, and the second group completed 15%, so they produced 1 18 more parts than originally planned. How many parts did each group originally plan to produce this month?

7. The number of parts produced by three workers, A, B and C, in a factory every day is 3: 4, B and C are 2: 3 ... If the number of parts produced by B every day is 945 less than the sum of A and C, how many pieces will each worker produce?

8. In order to do a good job in water conservancy construction, a village plans to build a canal with a length of 800 meters and an isosceles trapezoid cross section.

(1) The design cross-sectional area is 1.6m2, the canal depth is 1m, and the width of the upper mouth of the canal is 0.8m wider than the bottom of the canal.

(2) A construction team undertakes the project and plans to complete it within the specified time. After working for 4 days, the equipment has been improved and the work efficiency has been improved. Every day, the canal is dug 65,438+00 meters more than originally planned. As a result, the task was completed two days ahead of schedule, and the number of days required to complete the project was calculated.

9. This year, a school actively organized donations to support the disaster-stricken areas, and 55 students in one class donated money to 500 yuan. Donations are as follows:

There are two places in the table that I can't see clearly. Please help determine the data in the table.

Competition integral problem:

10. An enterprise conducted an English test for candidates, and the test questions consisted of 50 multiple-choice questions. According to the grading standard, if the answer to each question is correct, 3 points will be scored; if it is not selected, 0 points will be scored; if it is wrong, 1 point will be deducted. It is known that someone didn't do five questions and scored 103. So this person is wrong? Daoti

1 1. Eight classes in Grade 7 of a school held a football friendly match, which adopted a scoring system: 3 points for winning a game, 1 point for drawing a game, and 0 point for losing a game. After a class played 1 with seven other teams, it scored 17 points with an unbeaten record. How many games did this class win?

Age problem:

12.A is older than B. 15 years old. Five years ago, A was twice as big as B. Now B is _ _ _ _ _.

13. Xiaohua's father is 25 years older than Xiaohua now. Eight years later, Xiaohua's father is three times older than Xiaohua and five years older. Ask Xiaohua's age now.

Proportion problem:

14. The length of a part on the drawing is 32 cm, and the actual length is 4 cm. Then measure the length of another part of the diagram as 12cm, and find the actual length of this part.

15. In the first phase, the exchange rate between Japanese yen and RMB was 25.2: 1, so how much RMB can I exchange for 500,000 yen?

16. Teacher Wei went to the market to buy vegetables, and found that if 10 Jin of vegetables were put on the scale, the pointer on the dial turned to 180. As the picture shows, the next day, Teacher Wei gave the students two questions:

(1) If you put 0.5 kg of vegetables on the scale, how many angles will the pointer turn?

(2) If the pointer turns to 540, how many kilograms are these dishes?

(4) Distribution:

1. There are 64 people in the first workshop and 56 people in the second workshop of a factory. Now, due to the need of work, the number of people in the first workshop is required to be half of that in the second workshop. How many people should be transferred from the first workshop to the second workshop?

2. The number of team A is twice that of team B. After team A 12 is transferred to team B, the remaining number of team A is more than half of the original number of team B 15. What are the original numbers of teams A and B?

There are several workers in Workshop A and Workshop B respectively. If 100 people are transferred from Workshop B to Workshop A, the number of people in Workshop A is 6 times that of the remaining people in Workshop B; If 100 people are transferred from workshop A to workshop B, then the number of people in the two workshops is equal, and the original number of people in workshop A and workshop B is found.

(5) Distribution:

4. The school allocates student accommodation. If there are 8 people in each room, there will be less 12 beds. If there are 9 people in each room, two rooms will be available. Find the number of rooms and students.

5. School spring outing, if each car takes 45 people and 28 people don't get on the bus; If there are 50 people in each car, one car can be used and one car can take 12 people. How many students and cars are there?

Xiaoming has been studying for several days. If he reads 32 pages a day, there are still 3 1 pages left. If you read 36 pages a day, you need to read 39 pages on the last day to finish reading, and ask for the number of pages in the book.

(6) Supporting questions:

1. There are 28 workers producing bolts and nuts in a workshop, and each person can produce 12 bolts or 18 nuts per hour on average. How to distribute the workers who produce bolts and nuts so that the bolts and nuts match (one bolt with two nuts)?

2. There are 42 workers in the packaging factory, and each worker can produce 120 round iron sheets or 80 rectangular iron sheets per hour on average. Two round iron sheets can be combined into a sealed barrel. How to arrange workers to produce round or rectangular iron sheets?

3. A unit sent a team of 25 people to participate in flood control and flood fighting. If each person can load 18 bags of soil per hour or every two people can lift 14 bags of soil per hour, how to arrange manpower to make the mud loading and lifting work closely together, just to clear the field.

4. A workshop processes machine shafts and bearings, and a worker can process 15 machine shafts or 10 bearings on average every day. There are 80 people in this workshop, and a machine shaft and two bearings make up a set. How many workers should be assigned to process the machine shaft or bearing to make the machine shaft and bearing produced every day just match?

5. A factory produces a batch of suits, and 3 tops or 4 pairs of trousers can be cut every 2 meters of cloth. The existing tweed is 240 meters. How many meters should I use to cut my coat and trousers?

(7) Growth rate:

1. A chemical fertilizer factory produced 3,200 tons of chemical fertilizer last year, and plans to produce 3,600 tons this year, and this year plans to increase production by% compared with last year.

2. A processing factory has rice, and the rice yield is 70%. Now it processes rice 100 kg. If this rice is x kilograms, the correct equation listed is:.

A printing factory printed 500,000 scientific and technological books in the third quarter and 580,000 in the fourth quarter. What is the quarterly growth rate?

4. Two factories, A and B, completed the tasks of 1 12% and10% respectively last year, and * * * produced 4,000 machine tools, 400 more than the sum of the original tasks of the two factories. What is the initial production task of a factory?

5. The output of rape planted in a village last year reached 150kg, and the oil content was 40%. This year, the yield per mu increased by 30 kg and the oil content increased by 10 percentage point. Compared with last year, the planting area of rapeseed decreased by 40 mu, while the output of rapeseed produced by the village oil press increased by 20%. (1) Find the planting area of rape this year.

Suppose the planting area of rapeseed this year is X? Mu. Please complete the following table before listing the equation solutions.

(2) The known rape planting cost is 200 yuan/mu, and the purchase price of vegetable oil is 6 yuan/kg. Try to compare the net income of planting rape in this village in the past two years.

6. Civil aviation regulations: A passenger in ordinary class can carry up to 20 kilograms of luggage free of charge, and the excess can be purchased at 0/.5% of the air fare per kilogram/kloc. A passenger carries 35 kilograms of luggage, pays the air ticket and baggage fee 1323 yuan, and asks for the air ticket fare of the passenger.

Profit and profit margin:

7. A clothing store increased the cost of a certain dress by 40%, then marked the price and sold it at a 20% discount. Results Each garment still made a profit 15 yuan, and the cost of each garment was _ _ _ _ _ _ _.

8. After a 10% discount on a commodity, the price of each commodity is RMB, so the original price of each commodity is ()

If 25% of the price increase of a drug is 50 yuan, then the equation of price X before the price increase is _ _ _ _ _ _ _.

9. A shopping mall sets the price of each coat with the purchase price of X yuan at M yuan, and then reduces the price by 10%, and the customer has to pay 270 yuan. Given that the purchase price of X yuan is 60% of the purchase price of M yuan, the value of X is (? )

10. In order to participate in the market competition, the store will give 40 yuan a 10% discount on the selling price and still make a profit later 10%. The purchase price of this commodity is _ _ _ _ _.

1 1. If the purchase price of goods is reduced by 5% and the selling price remains unchanged, the profit rate can be increased by 15 percentage points. Find the original profit rate of this commodity.

12. A certain stationery is sold in a shopping mall, and each item makes a profit in 2 yuan. In order to support children in poor mountainous areas, they were given to a mountain school at a price of 30%, with a profit of 0.20 yuan each. What's the purchase price of this stationery?

13. Shanshan lighter factory produces some lighters. The cost of each lighter is 2 yuan, and the gross profit margin is 25%. By improving the technology, the factory reduced the cost, and the gross profit margin increased by 15% at the same price. Then the cost of each lighter has been reduced by _ _ _ _ _ _ _ _ _ _ (accurate to 0.0655).

14. The purchase price of a commodity 1500 yuan, and the price shall be marked after the price is increased by 40%. If it is sold at a discount, so its profit margin is 20%, how much discount will this product sell?

15. At a certain time, a store sold two pieces of clothes at the price of each piece in 60 yuan, of which one made a profit of 25% and the other lost 25%. Is selling these two clothes a profit or a loss, a profit or a loss?

16. Mom took Xiaoming to the stationery store to buy a schoolbag and pencil case. After bargaining, the original price of 42 yuan's schoolbag was 10% off and the original price of 18 yuan was 20% off. They must pay _ _ _ _ _ _ yuan as soon as possible.

17. the market demand D (1000 pieces) and the unit price p (yuan/piece) of a commodity obey the demand relationship:? Q:

(1) What is the market demand when the unit price is 4 yuan?

(2) If the unit price is increased by 1 yuan on the basis of 4 yuan, what will happen to the demand?

18. Lily's uncle saved 25,000 yuan earned by working in a bank for three years, with an annual interest rate of 3.24%. After three years, the principal and interest will be * * *? Yuan (excluding interest tax)

I saved an education savings account of 3,000 yuan three years ago, and the total principal and interest due this year is 3,243 yuan. Please help me calculate the annual interest rate of this savings account. If the annual interest rate is x%, the equation _ _ _ _ _ _ _ _ _ _ _ _ _ _ _. (Annual storage interest = principal × annual interest rate × year)

19. According to the national regulations, the deposit interest tax = interest ×20%, and the annual interest rate of one-year fixed deposit of the bank is 1.98%. Xiao Ming has a one-year fixed deposit. If he withdraws it all at maturity, he can get it back 12 19 yuan. If Xiaoming's one-year time deposit is X yuan, the correct one in the following equation is ().

(8) Quantity:

1. has a three-digit number, which is twice as big as the hundred digits, and the ten digits are bigger than the hundred digits 1. If the new number obtained by exchanging these numbers in the order of hundreds (from one digit to hundreds) is 49 times less than the original number, find the original number.

2. The highest digit in the five digits is 2. If you move this number to the right of the single digit, you will get three times the original number, and you will find the original number.

3. Arrange the consecutive odd numbers 1, 3, 5, 7, 9 ... in the following table:

(1) What is the relationship between the average of five numbers in the cross box and 15?

(2) If you translate the cross box up, down, left and right, you can frame five other numbers. Can the sum of these five numbers be equal to 3 15? If yes, request these five numbers; If not, please explain why.

(9) Geometric problems:

1. The circumference of the rectangle is 26 cm. If the length of a rectangle is reduced by 1cm and the width is increased by 2cm, it can become a square. Let the length of the rectangle be cm, and the equation listed is?

2. Fill a conical container with a bottom diameter of 30cm and a height of 8cm with water, and then pour the water into an empty cylindrical container with a bottom diameter of 10cm. How high is the water in the cylindrical container?

3. Forge a cubic iron block with a side length of 20cm into a cuboid iron block with a length of 100cm and a width of 5cm, and find the height of the cuboid iron block.

4. Put the cubic iron block with a side length of 20 cm into the measuring cylinder filled with water. It is known that the bottom area of the measuring cylinder is 12cm2. How many centimeters has the water surface in the measuring cylinder increased?

5. As shown in the figure, the area of the overlapping part of two rectangles is equivalent to one sixth of the area of the large rectangle, one quarter of the area of the small rectangle, and the area of the shaded part is 224cm2. Find the area of the overlapping part.

(10) Scheme design and cost analysis:

1. If a green vegetable produced in a certain place in our province is directly sold in the market, the profit per ton will be 1000 yuan. After rough machining, the profit per ton can reach 4500 yuan, and after finishing, the profit per ton can reach 7500 yuan.

A local agricultural, industrial and commercial enterprise bought 65,438+040 tons of this vegetable. The production capacity of the processing plant in this enterprise is: if the vegetables are roughly processed, they can process 16 tons per day, and if they are finely processed, they can process 6 tons per day, but the two processing methods cannot be carried out at the same time. Limited by seasonal conditions, the enterprise must sell or process all these vegetables within 15 days, and the enterprise has formulated three feasible schemes.

Scheme 1: Roughing all vegetables;

Option 2: Refine as many vegetables as possible, and sell the vegetables that can't be processed directly in the market;

Scheme 3: It takes 15 days to finish processing some vegetables and roughly process the remaining vegetables.

Which scheme do you think is the most profitable? why

The milk processing factory has 8 tons of fresh milk. If you sell fresh milk directly in the market (8 tons can be sold every day), you can get the profit of 500 yuan per ton; Made into yogurt for sale, you can make a profit per ton of fresh milk processed 1 200 yuan; Made into milk slices for sale, you can get a profit of 2000 yuan per ton of fresh milk processed/kloc-0. The production capacity of this factory is: if you make yogurt, you can process 3 tons of fresh milk every day; If you make milk slices, you can process fresh milk 1 ton every day; Due to the limitation of personnel and equipment, the two treatment methods cannot be carried out at the same time. Due to the limitation of temperature conditions, all milk must be sold or processed within 4 days.

Please help the milk processing factory to design a plan, so that all 8 tons of fresh milk can be sold or processed within 4 days, and you can get the maximum profit.

3. A theater in a city holds a large-scale cultural performance, and its fare is: first-class 300 yuan/person, second-class 200 yuan/person, third-class seat 150 yuan/person. A company organized 36 employees to watch and planned to buy two kinds of tickets with 5850 yuan. Please help the company design a possible ticket purchase scheme.

4. The taxi pricing rules in a city are as follows: the journey is less than 3km, and the starting price is 8 yuan. For the excess, the fare per kilometer is 1.2 yuan. One day, Mr. Zhang and three classmates went to visit a student and left 1 1km. Would you please calculate the fare payable by Mr. Zhang? Yuan.

According to Chutian Metropolis Daily, the domestic water price in Wuhan will be adjusted for the fourth time since 1999, and the domestic water price will be measured by steps. Urban water users (registered population of 4 and below) whose monthly water consumption is less than 22 cubic meters are the first type of water base, which is charged according to the adjusted domestic water price; More than 22 cubic meters and less than 30 cubic meters (including 30 cubic meters) are the secondary water base, which is charged at 0.5 times the adjusted price of 65438+; The part exceeding 30 cubic meters is the three-level water base, which is charged at twice the adjusted price. It is known that the adjusted domestic water price will increase from the current price of 1.5 1 yuan per cubic meter to 1.96 yuan. Mr. Zhang, a family of three, calculated the monthly water consumption at home and paid 74.48 yuan a month according to the current new price. Excuse me, Mr. Zhang's family Compared with before the adjustment, how much more water does his family pay each month on average?

Xiaoming's family moved to a new house to buy a new refrigerator. Xiaoming and his mother took a fancy to two kinds of refrigerators in the mall. The price of refrigerator A is 2 100 yuan, and the daily power consumption is 1 kwh. Refrigerator B is a new energy-saving product, the price is 2220 yuan, and the power consumption is 0.5 degrees per day. The effect of the two refrigerators is the same. The boss said that refrigerator A can be discounted, but refrigerator B can't be discounted. Please calculate the price and explain that it is more economical to buy refrigerator A if it is at least discounted. (The service life of 0.5 yuan per kilowatt-hour is 10 year, with an average of 300 days per year).

7. A class will buy some ping-pong balls and ping-pong bats. The situation is as follows: two stores, A and B, sell the same brand of table tennis and table tennis bats. Each table tennis bat is priced in 30 yuan, and each box of table tennis is priced in 5 yuan. After negotiation, a store gives a box of table tennis for every racket it buys, and B store gives a 10% discount on the pricing. This class needs 5 sets of rackets and several boxes of table tennis (no less than 5 boxes). Q: (1) When buying many boxes of table tennis, are the two preferential payment methods the same? (2) When buying 15 boxes and 30 boxes of table tennis, please do the following. Which store are you going to buy? Why?

8. A company is in urgent need of a car, but it doesn't need to buy one. They will evaluate the monthly car rental contracts of private cars or state-owned leasing companies. The monthly rental fee for individual car owners is 3 yuan/km, and the monthly rental fee for state-owned rental companies is 2000 yuan. In addition, 2 yuan is charged for every 1 km. Try to discuss which company's car is more economical according to the official distance.

9. A farmer contracted several hectares of barren hills in 2000, and invested 7,800 yuan to plant 2,000 fruit trees. The total fruit output this year is18,000 kg. This kind of fruit costs A yuan per kilogram in the market and B yuan per kilogram in the orchard.

① A and B respectively represent the income from selling fruits in two ways.

② If a= 1.3 yuan, and b= 1. 1 yuan, all fruits can be sold in both ways at the same time. Please choose which one is better through calculation.

10. Yucai Middle School needs to buy some teaching instruments. Scheme 1:? Go to the business to buy? Everything needs 8 yuan; ? Option 2:? The school made it itself. Every 4 yuan? In addition, the monthly rental fee for making tools is 120 yuan. X pieces of instruments are needed.

(1) express the cost of the two schemes with X trial algebra; ? (2) When and how many instruments are needed? The cost of these two schemes is the same. (3) When and how many instruments are needed? Which scheme requires less cost explains why.

1 1. A telecommunications company has opened two local mobile communication services, A and B. A users need to pay the monthly fee of 15 yuan, and then each call is 1 minute. Pay the phone bill again, 0.3 yuan; B users don't pay the monthly fee. Every call 1 min. Pay the phone bill, 0.6 yuan. If the talk time is X minutes within one month, the expenses of Party A and Party B are y 1 and y2 respectively.

(1), try asking someone to make a phone call for 30 minutes. What kind of communication service should he choose?

(2) According to the call time of one month, which communication service do you think is more favorable?

12. On National Day, the headmaster of a school led the "three good students" of the whole school to travel abroad. A travel agency said that "if the principal buys a ticket, the other students can enjoy a half-price discount", and B travel agency said that "all students including the principal enjoy a 60% discount on the ticket price" (that is, the fee is charged at a 60% discount on the ticket price). Now the whole fare is 240 yuan, and the number of students is 5. Please calculate which travel agency offers discounts. Which travel agency do you like? What if it's a principal and two students?

13. According to the statistics of the electric power department, 8︰00 to 2 1︰00 every day is the peak period of electricity consumption, and 2 1︰00 to 8︰00 the next day is the low period of electricity consumption, which is referred to as "low period" for short. In order to alleviate the contradiction of tight power supply demand, the power department of our city plans to gradually replace the "peak-valley time-sharing" meters and implement the new policy of "peak-valley time-sharing price", as shown in the following table:

Xiao Ming's family calculated the initial electricity consumption of 95 kwh after changing the watch. After calculation, it saves 5.9 yuan compared with the 95 kWh used before changing the meter. He let Xiao Ming's family use the "rush hour". Electricity and "valley time"? How many degrees is the electricity?

14. Xiaoming wants to choose two kinds of lamps, one is 10W (0.0 1KW) energy-saving lamp, 50 yuan, and the other is 100W (0. 1KW) incandescent lamp, 5 yuan. The lighting effect of the two lamps is the same.

(1) Which lamp is more economical to choose for lighting for 500 hours? (2) Lighting time 1500 hours, which lamp is more economical?

(3) How long does it take to use two kinds of lights for lighting?

15. Some of the same rooms need painting. Three masters painted eight rooms a day, and as a result, 40㎡ of the walls were not finished in time. Meanwhile, five apprentices painted the walls of nine rooms. Each master draws 30㎡ more walls than his disciples.

(1) Find the wall area to be painted in each room;

(2) Boss Zhang has 36 such rooms that need painting. If 1 master is invited to take two apprentices, how many days will it take?

(3) It is known that the daily wages of master and apprentice are 85 yuan and 65 yuan, respectively, and Boss Zhang requires that it be completed within three days. How to recruit people from these eight people?

(1 1) Classical Mathematics:

1. 100 monks 100 steamed stuffed buns, two for each big monk and one for each young monk. Ask how many big monks there are and how many young monks there are.

There are some chickens and rabbits. They have 88 heads and 244 feet. How many chickens and rabbits are there?

(12) concentration problem:

There are 5 kilograms of salt water with a salt content of 20%. To prepare salt water with a salt content of 8%, it is necessary to add _ _ _ _ _ _ _ _ kg of water.

A chemical plant has 175 kg of dilute sulfuric acid with a concentration of 15%. How many kilograms does 50% sulfuric acid need to be added to make 25% sulfuric acid?

Now it is necessary to prepare four kilograms of 20% pesticides with 80% concentration and 15% concentration. How many kilograms should I take each of these two pesticides?

The ratio of two alloys, A and B, silver and copper, is 4: 3 and 7: 9 respectively. Each alloy contains 84 kilograms of silver and 82 kilograms of copper. How many kilograms of new alloy can you get?

There are two kinds of alloys of copper and silver, A and B. The first alloy contains 25% silver and the second alloy contains 37.5% silver. Now, 65,438+000 kg of alloy containing 30% silver should be melted. How much should each alloy be taken?

(thirteen) set the auxiliary unknown:

1. A concert hall decided to hold a special concert for students during the summer vacation in early May. Admission tickets are divided into group tickets and retail tickets, of which group tickets account for 2/3 of the total votes. If you buy tickets in advance, you will be given different degrees of discount. May group tickets 12 yuan each, sold 3/5, retail tickets 16 yuan each. The price of group tickets is 16 yuan, and all the remaining tickets are planned to be sold in June. So how much should retail tickets be priced to make the ticket revenue of these two months even?

2.？ Now a commodity is reduced in price 10% for promotion. In order to keep the total sales amount unchanged, how many percent will the sales volume increase over the original price?