Teacher Wang bought 72 pens for the students, and spent □67.9△ yuan, of which I can't remember the math except □ and △. Please help the teacher with his math. How much is each pen? ※?
Smile and finish a bottle of juice four times. Drink one sixth of a bottle of juice for the first time, and then fill it with water. ※: The second time I drank a third bottle, then filled it with water, and the third time I drank half a bottle and filled it with water; Gulp it off for the fourth time. Drink less juice and drink less water.
A primary school numbers each student, with the numbers of boys ending in 1 and girls ending in 2. For example, 964 10252 means "I entered school in 1996, and my classmates are girls. ※. Then 0111kloc-0/01indicates that the student is a () student in Class () of Grade (), and his student number is (). If you are in Class 36, Grade 6, please fill in your student number in the above way.
There are two ways to pay for PHS mobile phones in a certain area: (1) free of monthly fee. 0.25 yuan per minute, basic monthly consumption 15 yuan. ※: (2) Pay the monthly fee of 18 yuan per month, and the call is 0. 1 yuan per minute. Please calculate the monthly call time as 100 minutes, 200 minutes. Which way is more cost-effective? If your father also has a PHS, which way do you think is better for him to pay? Why?
The tap water charge in a city is as follows: the monthly water consumption of each household15t (including15t) is charged according to one ton of 0.9 yuan; If it exceeds 15 ton, it will be charged as one ton in 3 yuan. A family used 2 1 ton of water in April. ※. How much should it pay for water?
Once, three friends, A, B and C, took a taxi to go out on business. When they set out, they agreed to share the fare reasonably. Get off 6 km early, 12 km, 18 km, pay the fare to 36 yuan. ※. How much fare do the three of them have to bear?
A peasant woman is carrying a basket of eggs to sell. The first time she sold half and more eggs, the second time she sold the remaining half and more, the third time she sold the remaining half and more, and finally there was an egg left in the basket. How many eggs does that peasant woman have? ※?
There are five boxes of biscuits in a food store. If you take out 15 kg from each box, the remaining five boxes of biscuits are exactly the original two boxes. How many kilograms of biscuits are there in each box? ※?
Xiao Liang and his father went for an outing by taxi. 5 yuan will be charged within 10 km, and 0.3 yuan will be charged every km beyond 10 km. When they get off the bus, Xiao Liang will pay 9.2 yuan's taxi fare. How many kilometers did they walk by taxi? ※?
Fifty-two students from Class Six (1) went to the aquarium. At noon, the teacher asked Beibei to buy drinks for everyone. Because I bought a lot, my aunt gave me a discount to buy one box and get one free. ※. * * * paid four boxes, one for each person. Do you know how many boxes there are in each box of drinks?
A primary school wants to buy 60 footballs, and now there are three stores A, B and C to choose from. The football prices of the three stores are all within 25 yuan, but the preferential measures of each store are different. ※:
Shop A: Buy 10 football and get 2 free; If you buy less than 10, you won't get them.
Shop B: 5 yuan is quoted for each football;
Shop C: After shopping in 200 yuan, I will return to 30 yuan.
In order to save money, which store should I go to to buy a primary school? Why?
The blaster wants to blow up an old bridge. According to the blasting situation, the safe distance is 70 meters (people beyond 70 meters must evacuate). Here are some known data. The personnel speed is 7m/s, and the fuze burning speed is10.3cm/s. How long should the fuse of this blasting be to ensure safety? ※?
A middle school library bought three hardcover editions and five paperback editions of A Chinese Dictionary, which cost 27.8 yuan. If you exchange one hardcover for two paperbacks, you have to pay 1 yuan. ※. How much is each hardcover dictionary?
There are three classes a, b and c in grade six. There are 50 students in Class A and Class B, 70 students in Class B and Class C, and 60 students in Class A and Class C. How many students are there in each class? ※?
Xiao Wanghua 140 yuan bought a coat, a hat and a pair of shoes. Coat be more expensive than hat, 90 yuan. ※. Coats and hats are more expensive than shoes 120 yuan. What is the price of a pair of shoes?
Party A, Party B and Party C each went out to 27 yuan to buy a batch of exercise books, and each went out to 9 yuan. Because Party B and Party C got 15 more copies than Party A, they each gave Party A 1.5 yuan. ※. How many exercise books did the three partners buy?
A primary school organized 325 teachers and students to go for a spring outing. It is known that the bus is limited to 40 people, each bus is limited to 1000 yuan per day, and the bus is limited to 25 people in 650 yuan per day. How to rent a car? ※?
There are two job advertisements. The salary of Company A adopts the annual salary system, with the starting salary of 1 10,000 yuan per year, and then it will increase year by year, and the 600 yuan will be increased every year. Company B adopts semi-annual salary system, with a starting salary of 5000 yuan every six months. ※. After that, 200 yuan will be added every six months. Which company offers more favorable terms?
A and B are going to explore the desert. They go deep into the desert for 20 kilometers every day. It is known that each person can carry food and water for up to 24 days. If you are not allowed to store some food on the way, ask: how many kilometers can one of them go deep into the desert? ※? What if some food can be stored on the way back?
Xiao Qiang, Xiao Wei and Xiaohua helped Li Nainai deliver two suitcases with the same weight to the station at a distance of 1.5km. They decided to split the task of running luggage equally, and each person could only carry one suitcase at a time. How many kilometers did everyone run on average? ※?
Party A, Party B and Party C run a 60-meter race. When Party A crossed the finish line, it was 10 meters ahead of Party B and 20 meters ahead of Party C. If the speed of each race remains the same, how many meters ahead of Party C will Party B cross the finish line? ※?
Aunt Li took 120 yuan to the market to buy meat. Because the price of meat was reduced by one fifth, she bought 5 kilograms more meat than the same money last time. Q: What is the original price per kilogram of meat? ※?
The original price of movie tickets was several yuan. Now, the price of each ticket is reduced by 3 yuan, the audience has increased by half, and the income has also increased by one-fifth. How much is a movie ticket? ※?
1. Someone wrote a program, starting from 1, alternately doing multiplication or addition (the first time can be addition or multiplication), adding 2 or 3 to the result of the last operation each time; Multiply the result of the last operation by 2 or 3, such as 30, and you can get:1+3 = 4 * 2 = 8+2 =10 * 3 = 30. How can I get: 100 times of 2+97 times of 2-2?
Answer: 1+3=4+2=2 thrice -2=2 thrice +2-2=(2 thrice +2 -2) * 2 =...= =2 100 times +2 97 times -2 97 times =2 65438.
This poem was written by Xu Ziyun, a mathematician in Qing Dynasty. Please figure out how many monks there are in this poem.
The majestic ancient temple is in the clouds. I wonder how many monks there are.
364 bowls, see if they are used up.
Three people eat a bowl and four people eat a bowl of soup.
Excuse me, sir, how many monks are there in the temple?
Answer: three people eat one bowl: then one person eats the third bowl.
Four people eat a bowl of soup: one person eats soup with a quarter bowl.
A total of1/3+1/4 = 7/12 bowls for each person.
Let * * * have x monks, according to the meaning of the question:
7/ 12X=364
Solution, X=624.
3. Two boys each ride a bicycle, starting from two places that are 20 miles apart (1 mile+1.6093 km). At the moment they set off, a fly on the handlebar of one bicycle began to fly straight to another bicycle. As soon as it touched the handlebar of another bicycle, it immediately turned around and flew back. The fly flew back and forth, between the handlebars of two bicycles, until the two bicycles met. If every bicycle runs at a constant speed of 10 miles per hour and flies fly at a constant speed of 15 miles per hour, how many miles will flies fly?
Answer: The speed of each bicycle is 10 miles per hour. After 1 hour, the two will meet at the midpoint of the distance of 2O miles. The speed of a fly is 15 miles per hour, so in 1 hour, it always flies 15 miles.
4. Sunzi Suanjing is one of the top ten famous arithmetical classics in the early Tang Dynasty, and it is an arithmetic textbook. It has three volumes. The first volume describes the system of counting, the rules of multiplication and division, and the middle volume illustrates the method of calculating scores and Kaiping with examples, which are all important materials for understanding the ancient calculation in China. The second book collects some arithmetic problems, and the problem of "chickens and rabbits in the same cage" is one of them. The original question is as follows: let pheasant (chicken) rabbits be locked together, with 35 heads above and 94 feet below. Male rabbit geometry?
A: If X is the pheasant number and Y is the rabbit number, then there is
x+y=b，2x+4y=a
Solution: y = b/2-a,
x=a-(b/2-a)
According to this set of formulas, it is easy to get the answer to the original question: 12 rabbits, 22 pheasants.
Let's try to run a hotel with 80 suites and see how knowledge becomes wealth.
According to the survey, if we set the daily rent as 160 yuan, we can be full; And every time the rent goes up in 20 yuan, three guests will be lost. Daily expenses for services, maintenance, etc. Each occupied room is calculated in 40 yuan.
Question: How can we set the price to be the most profitable?
A: The daily rent is 360 yuan.
Although 200 yuan was higher than the full price, we lost 30 guests, but the remaining 50 guests still brought us 360*50= 18000 yuan. After deducting 40*50=2000 yuan for 50 rooms, the daily net profit is 16000 yuan. When the customer is full, the net profit is only 160*80-40*80=9600 yuan.
6. Mathematician Weiner's age: The cube of my age this year is four digits, and the fourth power of my age is six digits. These two numbers only use all ten digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. How old is Weiner?
Answer: Let Wiener's age be X. First, the cube of age is four digits, which defines a range. The cube of 10 is 1000, the cube of 20 is 8000, and the cube of 2 1 is 926 1, which is a four-digit number; The cube of 22 is10648; So 10 =
7. The natural numbers of 1, 2, 3, 4 1987 ... 1986, 1987 are evenly arranged in a big circle, counting from 1: every 1 cross 2 and. Cross out 5 and 6 every 4, so that two numbers are crossed out every other number, and then circle. Q: How many numbers are left in the end?
Answer: 663
8. Stick a gold paper edge with the same width on the periphery of a landscape painting with a length of 90cm and a width of 40cm to make a wall chart. If the landscape painting area is required to account for 72% of the whole wall chart area, what should be the width of the gold paper edge?
Answer: (90+2X)(40+2X)*72%=90*40.
(90+2X)(40+2X)=3600/0.72
3600+ 180X+80X+4X2=5000
4X2+260X- 1400=0
(4X-20)(X+70)=0
Get 4x-20=0 X+70=0.
4*x=20 X=5
X=-70 does not hold.
So X=5CM.
9. Football made of black and white leather blocks, black leather blocks are regular pentagons and white leather blocks are regular hexagons. If there are 32 black and white leather blocks on a ball, please count the number of black and white leather blocks.
A: Equivalence:
The number of edges used in white skin and black skin = the number of edges used in black skin and white skin.
Set: there is a white skin X.
3x=5(32-x)
The solution is x=20.
10. There are ten identical black socks in Shuang Yi and ten identical white socks in Shuang Yi in the drawer. If you open a drawer in the dark and reach for your socks, how many socks do you have to take out to make sure you get a pair?
Answer: 3
1 1. Xiao Zhao, Xiaoqian, Sun Xiao and Xiao Li discuss which team won the final of the football match. Xiao Zhao said, "Team D will lose, but Team C can win." Penny said, "Team A and Team C are better than Team B, and there will be losses at the same time." Sun Xiao said: "Team A, Team B and Team C can all win." Xiao Li said, "Team A lost, while Team C and Team D obviously won."
They have said which team won. Can you guess which team won the championship?
Answer: Xiao Zhao, Xiao Gan, Sun Xiao and Xiao Li discussed which team won the final of the football match. Xiao Zhao said, "Team D will lose, but Team C can win." Penny said, "Team A, Team C will win and Team B will lose at the same time." Sun Xiao said: "Team A, Team B and Team C can all win." Xiao Li said, "Team A lost, while Team C and Team D obviously won."
Xiao Zhao's words indicate that Team D lost.
Small money means that team B lost.
Sun Xiao's words indicate that Team D lost.
Xiao Li's words showed that Team A lost.
So, Team C won.
12. If three line segments with lengths A, B and C can form a triangle, can the root numbers A, B and C of the line segments form a triangle?
If yes or no, please prove it.
If not, please give an example.
Answer: Yes.
Assuming that A is the smallest and C is the largest, the necessary and sufficient condition for abc to form a triangle is A+B >; c；
At this time, the comparison between √a+√b and √c is actually the comparison between √ a+b+2√ab and C (both sides are squares). a+b is already greater than C, and obviously a triangle can be formed.
13. A farmer met the devil, and the devil said, "I have an idea that will make you rich! As long as you cross the bridge behind me, your money will double. When you come back, your money will double every time you cross the bridge, but you must make sure that you give me a steel plate every time after you double your money. The farmer was overjoyed and immediately crossed the bridge. After crossing the bridge three times, there is only one steel plate left in his pocket, and he will pay the devil nothing left. Please use a single item containing a to indicate the number of steel plates in farmers' initial pockets.
Answer: let the initial amount be X.
2[2(2x-a)-a]-a=0
X=7a/8 to solve this equation.
14. Three students came home from school and saw a yellow car on the road. When they walked on, they heard that the car hit an old man and ran away. But no one wrote down the license plate number of this car. When the police asked the three middle school students, they all said that the license plate number was four digits. One of them remembers that the first two digits of the number are the same, another remembers that the last two digits of the number are the same, and the third remembers that the four digits are exactly the same.
A: Four digits can be expressed as
a× 1000+a× 100+b× 10+b
= a× 1 100+b× 1 1
= 1 1×(a× 100+b)
Because A × 100+B must be divisible by 1 1, A+B = 1 1 is brought into the above formula.
Four digits =1/kloc-0 /× (a×100+(1-a))
= 1 1×(a×99+ 1 1)
= 1 1× 1 1×(9a+ 1)
As long as 9a+ 1 is a complete square number.
Verified by a = 2, 3, 4, 5, 6, 7, 8 and 9, 9a+ 1 = 19, 28, 27, 46, 55, 64 and 73.
So there is only one solution with a = 7; b=4 .
Therefore, the four digits are 7744 =112× 82 = 88× 88.
15. It is known that 1 plus 3 equals to the second power of 4, 1 plus 3 plus 5 equals to the third power of 9, 1 plus 3 plus 7= 16 equals to the second power of 4, 1 plus 3 plus 5 equals to the second power of 25 equals to 5, and1plus 3 plus 9 equals to the second power of 5. ......
& lt 1 & gt； Imitate the above example and calculate 1 plus 2 plus 3 plus 5 plus 7 plus ... plus 99 equals?
& lt2> According to the above law, please use the natural number n(n is greater than or equal to 1) to express the general law.
Answer:
& lt2>1+3+5+...+n = the square of [(n-1)/2+1].
16. Once, a cat caught 20 mice and arranged them in a row. The cat announced its decision: first, eat the odd-numbered mice, then renumber the remaining teachers by 1, 2, 3, 4 ... and then eat all the odd-numbered mice. Repeat this operation and the last mouse will be released. A clever mouse listened and immediately chose a position. Finally, it was him, and the cat let him go!
Do you know where this clever little mouse is standing?
Answer: Rank 16. 1 remains divisible by 2, 2 (the square of 2) remains divisible by 4, 3 (the third power of 2) remains divisible by 8, and 4 (the fourth power of 2) remains divisible by 16, so only 16 will not be eaten.
17. 1/( 1*2*3)+ 1/(2*3*4)+ 1/(3*4*5)+…+ 1/(98*99* 100)
Answer:1(1* 2 * 3)+1(2 * 3 * 4)+1(3 * 4 * 5)+…+1(98 * 99).
=( 1- 1/2- 1/3)+( 1/2- 1/3- 1/4)+( 1/3- 1/4- 1/5)+...... 1/98- 1/99- 1/ 100
= 1- 1/ 100
=99/ 100
Remarks:1(1* 2 * 3) =1-1/3.
18. Xiao Wei and Xiaoming exchanged activities during the summer vacation. Xiao Wei said, "I attended the summer camp for science and technology and went out for a week. The sum of the dates of these seven days is 84. Do you know what date I left? " Xiao Ming said: "I stayed at my uncle's house for seven days during the holiday, and the date and number of months were also 84." Guess what date I went home? "
Answer: Question 1: Let the departure date be X.
X+X+ 1+X+2+X+3+X+4+X+5+X+6 = 84
X=9
Xiao Wei set out on the 9 th.
Question 2: Because it is a summer vacation activity, it can only be held in July and August.
Set the date back to x.
rank
7+X+X- 1+X-2+X-3+X-4+X-5+X-6 = 84
or
8+X+X- 1+X-2+X-3+X-4+X-5+X-6 = 84
The first formula solves X= 14.
The result of the second formula is not an integer.
So I can only get home in July 14.
19. A school has three classes: A, B and C. Class A has 4 more girls than Class B, and Class B has/kloc-0 more girls than Class C. If the first students of Class A are transferred to Class B, the first students of Class B are transferred to Class C, and the first students of Class C are transferred to Class A at the same time, the number of girls in the three classes is exactly equal. It is known that there are two girls in the first group of Class C. How many girls are there in the first group of Class A and Class B?
Answer: We assume that there are M and N girls in the first group of Class A and Class B respectively. There are x girls in Class B, so there are x+ 1, and there are x+5 girls in Class A, with an average of x+2 (calculated by variation). Class c:-2+n = (x+2)-X.
Class a: +2-m=(x+2)-(x+5) can get m=5 n=4.
20. There is a reservoir, which has a certain water flow per unit time and is also discharging water. According to the current flow rate, the water in the reservoir can be used for 40 days. Due to the recent rainfall in the reservoir area, the amount of water flowing into the reservoir has increased by 20%. If the discharged water volume is also increased by 10%, it can still be used for 40 days. Q: If the water is discharged according to the original discharge, how many days can it be used?
Answer: Let the total water volume of the reservoir be X, and the daily water inflow and water outflow are M and N respectively.
Then x/(n-m) = 40 = x/[n (1+10%)-m (1+20%)] needs x/[n-m( 1+20%)].
You can simplify n=2m x=40m and bring it into the second formula to get x=50 days.
2 1. A hotel first sets the temperature of air conditioners A and B to 1 degree. Results Air conditioner A saves 27 degrees more electricity than air conditioner B every day, and then the equipment of air conditioner B is cleaned, so that the total power saving of air conditioner B is 1.1times that of air conditioner A after the temperature is raised, while the power saving of air conditioner A remains unchanged.
Answer: Assuming that only after the temperature increases by 1 degree, two air conditioners A and B will save X and Y degrees every day.
X-Y=27，
X+ 1. 1Y=405
X=207
Y= 180
A and B air conditioners save electricity by 207 180 degrees each day.
22. The existing barren hills in Hongmian Village are 1 1,000 hectares, and the greening rate is 80%. There is no need to afforest 300 hectares of fertile land. The greening rate of trees on the river slope of X hectares this year is 20%, so the greening rate of all land in Hongmian Village will reach 60%. How many hectares of river slopes are there?
Answer: (x * 20%+1000 * 80%)/(1000+300+x) = 60%.
(0.2*x+800)/( 1300+x)=0.6
0.2*x+800=780+0.6*x
X=50 hectares
23. A piece of paper is 0.06 cm thick, and the distance from the earth to the moon is 3.85 * 10 5 km.
Xiao Ming said, if you cut this paper into two equal parts, pile up the paper cut into two equal parts and cut it into two equal parts. If it is repeated, the height of all the papers will be greater than the distance from the moon to the earth.
Xiao Gang said, I don't believe what Xiao Ming said.
Is Xiao Ming's statement correct Why?
Answer: 40 cuts are higher than 3.85 *10.5 km.
2 40 * 0.06/100000 = 6.597 *105km.
Xiao Ming is right, but the paper must be big enough, otherwise it won't be cut several times.
24. There are 27 pearls, one of which is fake, but its appearance is the same as that of a real pearl, only a little lighter than that of a real pearl. Q: If you weigh it with a balance at least a few times (without weights), you can definitely find out the fake pearls?
Answer: 3 times
For the first time, divide 27 pearls into 3 equal parts, take 2 of them and weigh them at both ends of the balance. If the balance is tilted, consider 9 light pearls; if not, consider 9 unweighted pearls. In the same way, divide nine pearls into three equal parts, weigh two at each end of the balance, and get three "suspicious" pearls again. Take out two scales. If the balance is crooked, the light one is defective ~ otherwise, the unweighed one is defective.
25. Like China, Egypt is also a famous ancient civilization in the world. The ancient Egyptians treated scores differently. Generally, they only use fractions whose numerator is 1, such as1115 for 2/5 and 1/4 for 65438. 1/90。 1/9 1, where whether to add 10, and add a sign to make it sum to-1, if it exists, please write down the number of 10, if not, please explain the reason.
Answer: Solution:
- 1=- 1/5- 1/6- 1/8- 1/9- 1/ 10- 1/ 12- 1/ 15- 1/ 18- 1/20- 1/24
Two solutions:
1- 1/2+ 1/2- 1/3+ 1/3- 1/4+ 1/4- 1/5+ 1/5- 1/6+ 1/6- 1/7+ 1 /7- 1/8+ 1/ 8- 1/9+ 1/9- 1/ 10= 1- 1/ 10
So:
1/2+ 1/6+ 1/ 12+ 1/20+ 1/30+ 1/42+ 1/56+ 1/72+ 1/90+ 1/ 10= 1
Namely:
- 1/2- 1/6- 1/ 12- 1/20- 1/30- 1/42- 1/56- 1/72- 1/90- 1/ 10=- 1
24. Three people go to a restaurant for dinner, and each person takes out 10. Three people pay the boss 30 pounds after eating, and the boss gets back 5 pounds and asks the waiter to give it to them. The waiter thought, how can I divide 5 pounds among three people? So he took out a tip of 2 pounds and left 3 pounds for each of the three people, so everyone paid 9 pounds and 27 pounds for the meal, but with the 2 pounds taken away by the waiter, it was 29 pounds. Where did the remaining 1 pound go?
25.n playing cards numbered 1, 2, 3 ... n are stacked together in order. Now deal the first card (number 1), put the next card (number 2) at the bottom of the pile, then deal the next card (number 3), and so on until all the cards are dealt. Please answer this question:
(1) What was the last card? Specifically, when n =13,54, 1000, what are your results respectively?
(2) How are the original cards arranged according to 1, 2, 3, ... n? Algorithms and corresponding implementation programs are needed. In addition, when n =13,54, how are the cards arranged?
26. Li Bai, a great poet in the Tang Dynasty, often drank and wrote poems. The following poem "Li Bai buys wine" is a very interesting math problem:
Li Bai was walking in the street, carrying a pot to buy wine.
When you meet a store, double it and fight with flowers.
I met the shop flower three times and drank all the wine in the pot.
Please guess, there is wine in the pot.
Why do you want this formula: 1 divided by 2 plus 1, divided by 2 plus 1, and finally divided by 2 equals 7/8 barrels.
26. There are four numbers: 5, 5, 1. Just add, subtract, multiply and divide, and the final result is 24. Note: squares, cubes and powers cannot be used.
27.
The rabbit family in modern society decided to compete with the tortoise family again in order to save the face of their ancestors who failed in the competition. In the afternoon, in order to show their strength, the rabbit family said that the tortoise should run 500 meters first (the whole journey is 2000 meters).
After receiving the gauntlet, the turtle family held a national meeting to discuss countermeasures. The tortoise can't win by strength, but it doesn't want to lose the face of its ancestors. Just then, a turtle appeared, claiming to outsmart his opponent.
Finally, the turtle replied: physical fitness is important in modern society, but intelligence is more important. We can beat you at the table. Why do you need a game? See you at the table if you have the courage!
The rabbit family thought that strength decided everything, and they were not afraid to serve, so they readily agreed!
At the table, the tortoise said, because of your arrogance, you lost the opportunity to save the face of your ancestors. The following is my discussion.
Let the speed of the tortoise be v 1 and the speed of the rabbit be v2. Because the rabbit runs 500m first, let the tortoise and the rabbit be so far apart, as shown in the figure.
a b c d
| - s0 - | - s 1 - | - s2 - | - s3 - |
Tortoise, tortoise, tortoise ...
Rabbit rabbit rabbit rabbit rabbit. ...
After the game starts, the tortoise plays A first, and then the rabbit runs. It takes time for the rabbit to run to A, and the tortoise to run to B within t 1. It takes time t2 for the rabbit to run to B and T2 for the rabbit to walk to C; It takes t3 for the rabbit to run to C, t3 for the tortoise to run to D, and so on. It can be concluded that the rabbit can only approach the tortoise infinitely, but can't catch up with the tortoise, so the rabbit can't win the tortoise.
The rabbit family thought for a long time, but found nothing wrong with the tortoise's reasoning. I regret letting the tortoise run 500 meters first. I regret that it is too late and I can only give up and go home.
But let's think about it. In reality, rabbits can catch up with turtles, but why? What's wrong with the turtle's reasoning?
27. There are 60 new apples of two sizes in the fruit shop. The price of a big apple is two yuan, and that of a small apple is three yuan.
It can be known that the total selling price of the big apple is 60/2 = 30 yuan, and the total selling price of the small apple is 60/3 = 20 yuan.
The new salesman accidentally mixed two kinds of apples, and * * * became 120 apple. Isn't it the same if he wants to sell it at the price of two yuan and five yuan each? But after he sold it, he got 120/5 * 2 = 48 yuan. But it should be 50 yuan. By the way, where did the two yuan go?
28A, b, c, d and four students participated in the table tennis singles competition. Before the game, four students said a word about the result:
A: "I will win the first place" B: "Neither A nor C will win the first place"
C: "A or B will win the first place" D: "B will win the first place"
As a result, two students were right. Q: Who will win the final?