Seek 32 application problems in the first semester of the first day of junior high school ~ urgent need! ! !

1. A swimming pool sells summer membership cards from June to August every year. Each membership card in 80 yuan is for personal use only. 1 yuan to buy tickets, 3 yuan does not buy tickets:

(1) Under what circumstances, does it cost the same to buy a membership card as not to buy one?

(2) Under what circumstances is it more cost-effective to buy a membership card than not to buy it?

(3) Under what circumstances is it more cost-effective to buy a membership card than to use it?

Note: The problem-solving process is complete, step by step, and can be solved by equation or equation.

80+X = 3 times

80=2X

X=40

X=40. Buying a membership card costs the same as not buying a membership card.

It is more cost-effective for X> to buy a membership card than not to buy one.

It is more cost-effective to buy a membership card if the X< membership card is not enough.

2. From place A to place B, go downhill first, and then take a flat road. Someone rode a bicycle downhill at 12km/h, crossed the flat road at 9km/h, and arrived at B. in 55 minutes. When he came back, he crossed the flat road at 8 km/h and went uphill at 4 km/h. It took 1.5 hours to get back to a place. How many kilometers is it from a to b?

Let the slope be x kilometers and the flat road be y kilometers.

Then there is

x/ 12+y/9=55/60

y/8+x/4= 1.5

X = 3, y = 6 to solve the equation.

So the distance between a and b is x+y=9.

3. Grade one 1 class took 100 trees, leaving 10. Grade one and grade two took 200 trees, leaving 10. How many classes are there in grade one in .......................................................................................................?

Suppose there are x trees.

100+(x- 100)/ 10 = 200+[x- 100-(x- 100)/ 10-200]/ 10

100+x/ 10- 10 = 200+x/ 10- 10-x/ 100+ 1-20

x=8 100

So the first lesson took100+(8100-100)/10 = 900 trees.

A total of 8 100/900=9 categories.

4. When the thunderstorm duration t (hours) can be estimated by the formula: t 2 = d 3/900, and d (kilometers) represents the diameter of the thunderstorm area.

The thunderstorm area is 6 kilometers in diameter. How long can a thunderstorm last?

Thunderstorm duration 1 hour. What is the approximate diameter of the thunderstorm area?

1、t^2=d^3/900

t^2=6^3/900

T = the square root of the

2、t^2=d^3/900

1^2=d^3/900

D= cube root 900

It is 800 kilometers from Station A to bilibili. At first, 400 kilometers are flat roads, then 300 kilometers are uphill and the rest are downhill. It is known that the speed ratio of the train is 3: 4: 5. If the speed of the train on the level road is 80km/h, it will take more time to get from Station A to bilibili than from bilibili to Station A. If the train takes the same time to go back and forth, what is the speed ratio of the train from Station A to bilibili and from bilibili to Station A on the level road?

Uphill speed: flat road: downhill =3:4:5, flat road speed =80,

So uphill speed =60, downhill speed = 100,

Time from A to B: 400/80+300/60+100/100 =11,

Time from B to A:100/60+300/100+400/80 = 29/3,

So 1 1-29/3=4/3 hours,

(2) Let the speed from A to B be X, and the speed from B to A be Y, according to the meaning of the question: 400/x+300/[(3/4) x]+100/[(5/4) x] = 400/y+300 [(5/4)

Solution: x/y=33/29

6. A school sports meeting will be held on the 400-meter circular runway 10000-meter competition. After two athletes started at the same time, B was faster than A, 15 points, A accelerated. 18 minutes, A catches up with B, starts to overtake B, 23 minutes, A surpasses B again, 23 minutes and 50 seconds, A reaches the finish line. So what's the time for B to finish the race?

18, A catches up with B, starts to overtake B, 23, A catches up with B again. Caption: A ran 400 meters more than B in 5 minutes. So the speed difference between Party A and Party B is 400 ÷ 5 = 80m.

2. 15, Party A speeds up. 18, Party A catches up with Party B and begins to overtake. Description: Party A caught up with Party B in 3 minutes, but the difference between them was 80×3=240 (meters), which was caused by Party B being faster than Party A in the first 15 minutes. So it turns out that Party B is faster than Party A..

3. Let the original speed of A be x meters per minute, and now the speed of A is x+96 meters per minute.

15x+(x+96)×(23 5/6- 15)= 10000。

x=384

So the original B speed: 384+ 16=400 meters.

B The time to finish the race is: 10000÷400=25 minutes.

When our army reached a bridge to stop the enemy from starting, the enemy was 24 kilometers away from the bridge and our army was 30 kilometers away from the bridge. The speed of our army's urgent March is the enemy's 1. The result was five times, 48 minutes earlier than the enemy. Seeking the speed of troops?

Set the enemy speed x km/min.

30/ 1.5x +48=24/x

x= 1/ 12

Army speed =1.5 *112 = 0.125.

8. A company sells two kinds of sneakers, A and B. Last year, it sold12,200 pairs. This year, the sales volume of type A shoes is 6% more than last year, and the sales volume of type B shoes is 5% less than last year. The total sales volume of two kinds of shoes has increased by 50 pairs. How many pairs of sports shoes did A and B sell last year?

Suppose last year Class A sneakers sold X pairs, then Class B sold (12200-x) pairs.

Then we will sell (1+6%)x Shuang Yi and other sneakers this year, and then sell (1-5%)( 12200-x) double second-class sneakers.

there is something wrong

12200+50 =( 1+6%)x+( 1-5%)( 12200-x)

12250= 1 1%+ 1 1590

1 1%x=660

x=6000

12200-x=6200

A: A sold 6,000 pairs and B sold 6,200 pairs.

9. I played chess with my grandson and played 12 (no draw). The score was the same. Grandpa won a game with 1, and grandson won a game with 3 points. How many games did grandpa and grandson win? Use equation

Solution: suppose grandpa wins the X game.

x=3( 12-x)

x=9

Sun Tzu won: 12-9=3 games.

10. A file needs to be printed. It takes 6 hours for Xiao Li to finish it alone, and 8 hours for Xiao Wang to finish it alone. How long will it take if they finish it together?

1/(1/6+1/8) = 24/7 hours.

1 1. In order to enable poor students to successfully complete their college studies, the state has set up a student loan. Student loans are divided into four types: 0.5~ 1 semester, 1~3 semester, 3~5 semester and 5~8 semester. The loan interest rates are 5.85%, 5.95% and 6.00 respectively. There is a calculator.

Set the maximum loan of x yuan.

(4 * 6.2 1% * 0.5+2 * 6.2 1%+ 1)x = 20000

Get X= 16020.506 yuan.

12 There is a football made of 32 pieces of black and white cowhide. Black leather is pentagonal, white leather is hexagonal, and their sides are all equal. Find the number of pieces of white leather and black leather.

Solution: If there are x white blocks, there are (32-x) black blocks.

5(32-x):6x= 1:2

x=20

32-x=32-20= 12 (piece)

A: There are 20 white blocks, 12 black blocks.

13. The fruit shop buys a number of apples, each at the price of 3 yuan. If you sell them every 5 yuan, when you sell more than half of all 10 apples, you can recover the full cost. How many apples were sold?

Set x apples.

3X=5X/2+ 10×5

X= 100 (piece)

14. By car, I originally planned to rent more than 30-seat buses, but none of the five people had seats. If you rent a 35-seat bus, you can miss one. Every bus is full. It is known that the rental of 30-seater cars 165 yuan and 35-seater cars10 yuan. How many people are there in the first grade?

Solution: Suppose the original plan was to rent X cars.

30X+5=35(X- 1)

30X+5=35X-35

-5X=-40

X=8

Therefore, the number of junior one students is 30× 8+5 = 245 (people).

15 someone originally planned to ride a bike from place a to place b at the speed of 12km per hour, so that they could arrive within the specified time. However, because of something, he delayed the original planned departure time by 20 minutes, so he had to go at the speed of 15km per hour, and finally arrived at B place four minutes earlier than the scheduled time, so as to find the distance between A place and B place?

The distance between a and b is x.

15x/ 12-(20+4)/60=x

x=24

16. Two candles with different compositions and the same length can be burned in 3 hours and 4 hours. It is now required that by four o'clock in the afternoon, the remaining part of one candle is exactly twice that of the other. Should these two candles be lit at the same time?

Solution: Set it to ignite x hours ago.

〈 1- 1/4X÷/〈 1- 1/3X÷= 2

X= 12/ 1 1

17.a and B are 5 10 km apart. Two cars, A and B, are driving in opposite directions from two places. If two cars leave at the same time, they will meet in five tenths of an hour. If B leaves two hours first, then A will meet four hours after departure. What is the speed of the two cars?

5 10÷5 and110 =100 (km) This is the sum of the speeds of two cars.

(510-100× 4) ÷ 2 = 55 (km) This is the speed of the second car.

100-55 = 45 (km) This is the speed of car A. ..

18. It is known that there are 5 A-type machines. 1 1 After filling 8 boxes, there are 4 products left, and after filling 6 boxes a day, there are 7 B-type machines left. Each type A machine produces 1 product more than the type B machine. How many products are there in each box?

Please use a linear equation to solve it.

Set: x per box

Analysis: 5 A machines 1 day produce 8 boxes of 4, so one A machine 1 day produces (8X+4)÷5.

Seven machines B can produce 1 1 box in1day, so one machine B can produce (1 1 x+1) 7 boxes in1day.

Because the title says: each A produces more than B 1 1 day.

The formula is (8x+4) ÷ 5-1= (11x+1) ÷ 7.

7(8X+4)-35 = 5( 1 1X+ 1)

56X-28-35=55X+5

56X-7=55X+5

56X=55X+ 12

X= 12

A: There are 12 products in each box.

19. The basic price of electricity for residents in a certain place is 0.4 yuan per kWh. If the monthly electricity consumption exceeds 60 kWh, the excess will be charged at 70% of the basic electricity price. In June, the average electricity bill per household was 0.36 yuan per kWh. How many kwh will be shared? How much is the electricity bill?

Suppose X is used in June.

60*0.4+(X-60)*0.4*70%=0.36X

x = 90°

That is to say, it took 90 degrees to pay: 90*0.36=32.4 yuan.

20. Party A and Party B climb mountains. Party A climbs10m every minute, and starts for 30 minutes first. Party B climbs15m every minute, and both of them climb the mountain at the same time. How long does it take Party A to climb the mountain? How high is this mountain?

Suppose A spent x minutes climbing the mountain, then B spent (x-30) minutes climbing the mountain, and both of them reached the top of the mountain at the same time.

10x+ 10 * 30 = 15(x-30)

X= 150 (minutes)

So the height of the mountain is:10x+10 * 30 =1800m.

2 1. A rides a bike from place A to place B, and B rides a bike from place B to place A, both of which advance at a constant speed. It is known that they started at 8: 00 a.m. at the same time, and they were still 36 kilometers apart at 10 in the morning and 36 kilometers apart at 12 at noon. Find the distance between a and B.

36+36x2= 108

Because it is driving at a constant speed, the speed is certain. After two hours in the morning, the distance is 36. After two hours, the distance is staggered by 36, so two hours is 72, which means two people walk together every hour. It is concluded that they also walked 72( 36x2) in the first two hours. Since they haven't met since 10, the distance is 36, so adding these 36 is two places.

22. If the absolute value of a+3 and the square of b-2 are reciprocal, find the value of the second act of A..

Both the absolute value and the mean square value are greater than or equal to 0, so:

a+3=0

b-2=0

a=-3

b=2

a^b=(-3)^2=9

23. The following are the advertisements of three companies:

Company A: Recruitment 1 person with an annual salary of 30,000. After one year, the annual salary increased by 2000 yuan.

Company B: Recruitment 1 person, annual salary 1, and increase by 20% every six months after half a year.

Company C: Recruitment 1 person, with a monthly salary of 2,000 yuan and a monthly salary increase of 100 yuan after one year.

Which company are you going to choose if you apply? (The contract term is 2 years)

A: 3+3.2 = 62000.

b: 1+ 1.2+ 1.2 * 1.2 * 1.2 = 1+ 1.2+

c:0.2 * 24+0.0 1+0.02+0.03+0.04+...0. 12 = 4.8+0.78 = 55,800.

A has the highest salary and went to A.

24. 1. The charging standard for group tickets in a scenic spot is: less than 20 people (including 20 people). Everyone in 25 yuan, if there are more than 20 people, each student 10 yuan will visit the scenic spots in a class of 5 1 students. How much is the ticket?

20 * 25+(51-20) *10 = 810 (yuan)

25.2. When a company sells a certain product, there are two schemes to pay the salesperson's monthly salary:

Option 1: No matter how much you sell, there is a basic salary in 600 yuan, and every product you sell will give you a promotion fee in 2 yuan;

Option 2: No basic salary is paid, and 5 yuan promotion fee is paid for each product promoted;

If Xiaoming sells 300 products a month, which salary scheme should he choose? Why?

Scheme 1: 600+2×300= 1200 (yuan)

Scheme 2: 300×5= 1500 yuan.

So the second option is cost-effective.

26. A certain store sells two pieces of clothes at the price of each piece of 60 yuan at a certain time, of which one makes a profit of 25% and the other loses 25%. Is it a profit or a loss to sell these two clothes, or is it a capital preservation?

Suppose the original price of one dress is X and the other is Y, then

X( 1+25%)=60，X=40。

Y( 1-25%)=60, and the result is Y=80.

Generally speaking, the selling price-original price, 40+80-60*2=0.

So no profit, no loss.

27. A store will first increase the original price of a color TV by 40%, and then write "big reward, 20% discount" in the advertisement. After the customer complains, the law enforcement department will impose a fine of 2700 yuan per set according to 10 times of the illegal income. What's the price of each color TV?

The illegal income is below 270 yuan.

Original selling price x

1.4x*0.8-x=270

x=2250

The original price is 2250 yuan.

28. A passenger in an ordinary cabin 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, and the baggage fee is paid 1323 yuan. What is the ticket price of this passenger?

Let the air ticket price be x, x+1.5% * x *10 =1323.

The fare is 1 150.43 yuan.

29. Xiaoming got 82 points in the first math test, 96 points in the second, and at least how many points in the third. The average score of these three tests is not less than 90 points?

If the average score is not less than 90 points, the total score is not less than 3*90=270 points.

So the third test should be at least 270-82-96=92.

30.a starts from a city by bike. Two hours later, B walked the same road for three hours, and the distance between them was 16km. At this time, B continued to catch up. A rested in the same place 1 1/3 hours, and then returned from the same place. 1 hour later, Party A and Party B will separate from point C. How far is point C from a city?

Let the speed of a be x km/s and the speed of b be y km/s. ..

Because B chased A for three hours, and A was advancing, there was an equation 5x-3y= 16.

A has a rest time of 1 1/3 hours, which is the time that A walks less than B. The distance they walk is 16KM.

Then there is the equation (1+11/3) y+x =16.

By solving the equation, we can get

Y= 192/79 (km)

x=368/79

Because A moved forward for 5 hours and returned to 1 hour, the distance between point C and point A should be 4 times that of X..

It should be 1472/79, or 18.633 KM.

That is, the distance from point C to point A is about 18.633km.

32. A company ordered X white shirts and Y flowered shirts in a store, and the price of each white shirt was one and a half times that of flowered shirts. When I bought shirts, I found that the numbers of white shirts and flower shirts were just changed to the original numbers. After checking, the order was filled in incorrectly, and the ratio of the amount of money required according to the original idea to the actual amount payable was expressed as a fraction.

If the price of a white shirt is Z, then the cost is 2z.

Imagine the amount: xz+2yz (note: the cost of x white shirts and y flowered shirts)

The actual amount is: 2xz+yz (note: the cost of X shirts and Y white shirts).

The result is: (x+2y)/(2x+y).

33. A school has a 199 teacher and student who want to rent a car to travel. If you rent an A-class station wagon that can take 45 people, rent a car in 400 yuan; If you rent a second-class station wagon that can take 32 people, rent a car in 300 yuan. If you rent two cars at the same time, what is the lowest cost? What's the minimum charge?

199=45*3+32*2

400 * 3+300 * 2 = 1800 yuan

34. The starting price of taxis in a city is 10 yuan (i.e., the fare within 5km is 10 yuan). When it reaches or exceeds 5km, 1 km is 1.2 (less than 1 km is also counted as 1 km).

)。 Now someone takes a bus from A to B, paying 17.2 yuan. What is the approximate distance from a to b?

Solution:

Because it's over 10 yuan, it's over 5 kilometers.

Let the distance be x kilometers.

(x-5)* 1.2+ 10 = 17.2

Solution: x= 1 1.

A: ......

35. The distance between the two places is 300KM, and there are ships sailing in the two places. If it takes 15H downstream and 20H downstream, what is the speed format of a ship sailing in still water against the current?

Understand first; Downstream speed = ship speed+current speed; Upstream speed = ship speed-current speed

Then the downstream speed * 15 is equal to the distance between the two places, and the upstream speed *20 is also equal to 300km.

Solution: Let the ship speed be X km/h and the current speed be y km/h. 。

15(x+y)=300

20(x-y)=300

The solution is x= 17.5 y=2.5.

Then when the speed of the ship in still water is 17.5km/ and the upstream speed is (17.5-2.5)= 15km/.

36. 1, 5, 1 yuan 10 coins, of which 15 coins were taken out, with a total value of 7 yuan. 1, 5, 1 How many coins are there?

Actually, 7 yuan is an integer:

Without 1 horn, there would be no 15 pieces.

2. If there are 1 angles, then there can only be 5 or 10 or 0 angles:

(1) If there are five blocks in 1, then the number of blocks in corner 5 should be singular, and the number of blocks in corner 5 can only be 9, 7 and 5. If we analyze 9 pieces, 7 pieces are just right and 5 pieces are not good, we can get a result: 5 pieces 1 angle, 7 pieces/50 angle and 3 pieces 1 yuan.

(2) If there are 65,438+00 of 65,438+0 angles, then the number of 5 angles should be even, and there are only 4,2,0 five angles (65,438+05 in total), so it is difficult to analyze 0, 2 and 4.

(3) If there is no 1 corner, then the minimum value of the combination of 15 and 1 yuan should be 10 and 5 1 yuan, totaling 10 yuan. No.

The final result is: 3 yuan for 1, 7 yuan for 5 corners, and 5 yuan for 1.

37. There are (5A-4) passengers on a bus, and (9-2A) passengers get off when they arrive at the station. How many passengers are there on the bus?

5a-4≥9-2a —— ①

9-2a>0 —— ②

A≥ 13/7 from ①

Get a < 9/2 from ②.

(5a-4) and (9-2a) should both be positive integers, so a must be an integer.

The integer solution satisfying 13/7 ≤ A < 9/2 is a1= 2; a2 = 3； A3=4, so there are 6, 1 1 or 16 passengers on the bus.

38. The school organizes students to practice in the countryside 3 1km away from the school, with 3 hours in the morning and 4 hours in the afternoon, and the average speed in the afternoon is slower than that in the morning 1km. What is the average speed in the morning and afternoon?

Let the morning speed be x and the afternoon speed be y.

X-Y= 1

3x+4y=3 1

Solution: X=5, Y=4.

That is, 5 kilometers in the morning and 4 kilometers in the afternoon.

39. A swimmer went upstream and lost an empty plastic kettle in one place. When he advanced 50 meters to B, he found that the kettle was lost and immediately returned to look for it. He found it in section C. This man's swimming speed is 0.5 times the current speed of 65438+. How many meters did he swim from losing it to finding the kettle?

Suppose the drifting distance of the kettle is x meters, the current speed is v meters/second, the swimmer's upstream swimming speed is 1.5V-V = 0.5V (m/s), and the downstream swimming speed is 1.5V+V = 2.5V meters/s, according to the meaning of the question (kettle drifting time = this person's swimming time).

50/0.5v+(50+x)/2.5v=x/v。

Solve this equation and get x = 200.

So I swam 50× 2+200 = 300 meters from the lost place and found the kettle.

40. There are three kinds of texts: A, B and C. If you buy two A's, 1 B's and three C's, you need 23 yuan. If you buy 1 A, 4 B and 5 C, you need 36 yuan. How much does it cost to buy 1 a, 2 b and 3 c?

Solution: Suppose that buying A costs X yuan, buying B costs Y yuan and buying C costs Z yuan, then

2x+y+3z=23

x+4y+5z=36

Simultaneous solution

y+z=7

x+z=8

Now x+2y+3z=x+z+2(y+z)=8+7*2=22 yuan.

So it costs 22 yuan to buy 1 piece A, 2 pieces B and 3 pieces C.

4 1.a and b practice running on the 400-meter circular track. If they run in the same direction, they meet every 3 minutes and 2 seconds. If you run relatively, meet every 40 seconds. What are the speeds of A and B respectively?

The velocities of a and b are x and y respectively.

(x+y)*40=400

(x-y)* 182=400

42.40-legged centipede and Hydreigon are in a cage. There are 26 heads and 298 feet. A centipede with 40 feet has only one head. How many feet does Hydreigon have?

Three unknowns, two equations.

A dragon has one foot, x centipedes and y dragons.

The countable equation is 40x+ay=298 (1).

x+3y=26 (2)

According to the formula 1, the possible solutions of x are 7, 6, 5, 4, 3, 2, 1, 0.

There are two formulas to get x=5, y=7 or x=2, y=8 (only y=7 and y=8 are divisible).

Substituting 1 can get a= 14.

43. There are 840 parts in one batch. If Party A does it for four days first and Party B joins the cooperation, it will take eight days to complete it. If Party B does it for four days first and Party A joins the cooperation, it will take nine days to complete it. How many pieces will two people make every day?

Suppose A produces X machine parts every day, and B produces Y machine parts every day.

(4+8)x+8y=840

9x+(4+9)y=840

Get a solution

x=50

y=30

A: Party A and Party B produce 50 and 30 machine parts each day.

Xiao Ming plays games with his classmates. He is required to go 20 meters ahead from a certain point, turn left 30 degrees, go 20 meters ahead and turn left 30 degrees until he returns to a certain point. How many meters did Xiaoming walk?

Solution: The last one is actually a polygon with positive 12.

360/30= 12。

Results: 20 *12 = 240 m.

45. 200 senior one students in a school took the mid-term exam. The average score of students who passed the math exam was 87, the average score of students who failed was 43, and the average score of senior one was 76. How many people passed and failed the exam?

Let the number of people who passed the exam be x and the number of people who failed it be y.

x+y=200

87x+43y=200*76

x= 150

y=50

46. A construction team wants to recruit workers A and B 150, and the monthly wages of workers A and B are respectively 1000 yuan in 600 yuan. Now Party B is required to be no less than twice that of Party A's workers. What is the minimum wage?

Suppose there are X people in Class A and Y people in Class B, and the sum of money is S.

2X is greater than or equal to y.

X+Y= 150

3X= 150

X=50

When 2X=Y, the money is the least.

600X+ 1000Y=S

600X+ 1000(2X)=S

Substitute X=50.

600*50+ 1000*(2*50)

=30000+ 100000

= 130000 yuan

A: There are 50 people in Party A, 0/00 people in Party B/kloc, and the minimum wage is 0/30,000 yuan.

Do a good job of quadratic function in grade three.

47. A shopping mall plans to allocate 90,000 yuan to buy 50 TV sets from manufacturers. It is known that the ex-factory prices of three different models of TVs produced by this manufacturer are A 1.5 million yuan, B 2 1.0 million yuan and C 2500 yuan respectively.

(1) If the shopping mall buys 50 TV sets of two different models at the same time, which costs 90,000 yuan, please study the purchase scheme.

(2) If a shopping mall sells a TV, what is the maximum profit of the scheme in 150 yuan, 200 yuan B, 250 yuan C, (1)?

Solution: set up A X, B Y and C Z stations.

Option 1: Buy both parties.

X+Y=50

1500X+2 100Y=90000

X=25 Y=25

Option 2: buy a and C.

X+Z=50

1500X+2500Z=90000

X=35 Z= 15

Option 3: buy b and C.

Z+Y=50

2500Z+2 100Y=90000

Y=-37.5 Z=87.5 (truncated)

So there are two options.

Scheme 1: 25* 150+25*200=8750.

Scheme 2: 35 *150+15 * 250 = 9000.

Option 2 is more profitable.

48. Hangzhou East Road, known as the urban landscape, spans the lake for1.857m, and its greening indicators are shown in the following table. Analyze the table and answer the following questions:

Number of main tree species

Zhangshu 336

Liu Shu 188

Palm 258

Osmanthus fragrans 50

A total of 832 people

It is known that Hangzhou East Road is 4744 meters long. When the row spacing (horizontal distance between two trees) is unchanged, please estimate the number of camphor and palm trees planted along the line (the result is an integer).

The plant spacing is 2.23m, the number of plants in the whole line is 4744/2.23+ 1=2 128, the proportion of camphor trees is 336/832, and the number of plants in the whole line is 2 128*336/832=859 palms =659.

49. Someone bought a one-year bond with a certain amount of RMB, with an annual interest rate of 65,438+00%. After the maturity, he took out half of the principal for shopping, and the remaining half and the interest earned all bought this one-year bond (interest unchanged). Upon maturity, I got the principal and interest and 1, 320 yuan. How much did the man spend on this bond?

1200 yuan

Suppose he spent X yuan to start buying bonds. According to the meaning of the question, the equation is:

x 10% 0.5+x+(x 10% 0.5)+(x 10% 0.5) 10% = 1320

The solution is x = 1200.

50. There are 20 questions in a math contest for first-year students in a school. For each correct answer, you get 5 points. 1 point will be deducted for each wrong answer or no answer. How many questions do I have to answer correctly to get 70 points?

Solution:

20× 5 = 100 (minutes)

100-70 = 30 o'clock

30 ÷ (5+ 1) = 5 channels.

20-5 = 15 channels

Answer: If you want to get a score of 70, you must get it right 15 and get it wrong 5 times ~

Finally, I'll give you a question _

5 1. 1. In China's stock market transactions, every transaction has to pay 7.5% of various fees. Xiao Wang bought 2000 shares of a Shanghai stock at the price of 10 yuan per share. When the share rises to how much yuan, he can make a profit 1685 yuan. (writing process)

2.。 —.—.——.

Post-ad century

As shown in the figure, C is the midpoint of AB and D is the midpoint of segment AC. Given that the sum of the lengths of all line segments in the graph is 39, find the length of line segment AC.

1 、( x- 10)* 2000-0.0075 *( 10+x)* 2000 = 1685

X= 1 1 yuan

2. let ad = X.

x+x+2x+2x+3x+4x=39

x=3

AC=2AD=2x=6