Time flies, the summer vacation on 20 17 has arrived. How can we let the majority of primary school students spend a happy and fulfilling summer vacation? The following is the answer to the fourth grade math homework I brought to you. I hope it will help you!

1. The students planted trees on one side of a 200-meter-long path, one at every 4 meters (both ends). How many seedlings does a * * * need?

Analysis: The key to this problem is to plant a tree at the starting point, and then walk 4 meters to carry a tree. There are 50 4 trees in 200 miles, so ***5 1 tree. Teachers can use this question to ask whether there are no seeds at both ends, or think about climbing stairs and chopping wood, and sum up their similarities and differences. (If trees are planted at both ends, add1; If no trees are planted at both ends,1should be subtracted; If you plant trees at one end, you should add and subtract. )

Formula: 200÷4+ 1=5 1

2. The distance between the two buildings is 60m, and a pine tree is planted every 5m. How many trees can be planted between two buildings? Analysis: The 1 question on this question is similar, and it belongs to the kind where no trees are planted on both sides. 1 title plus 1, minus 1 title.

Formula: 60÷5— 1= 13.

A square, if its adjacent sides are increased by 6 cm, can get a new square, and the area of the new square is larger than the original square 120 square cm. Find the area of the original square.

Analysis: This question should be combined with graphics to help children understand. The added part is a rectangle with a width of 6 and a length of 6+ positive side. Therefore, to ask for the area of the original square, we must find the side length of the square, and only ask for the length of the added rectangle.

Formula:120 ÷ 6-6 =14; 14× 14= 196。

1, there is a column number: 2, 5, 8, 1 1 4. Do you know what the number is 1995 according to the above arrangement rule?

Analysis: the difference between two numbers is 3, and the first number is: 3×1-1= 2; The second number is 3× 2- 1 = 5. What is the number? It is three times less than 1.

Formula: Solution: ∫ 2+3 = 55+3 = 88+3 =111+3 =14.

So: the nth = 3n- 1.

∴3× 1995— 1=5984

2. There is a triangular land with three sides of 120m, 150m and 80m respectively. Plant a tree every 10 meter at the boundary. How many trees can you plant at most?

Analysis: Triangle is a closed figure, that is, the starting point is also the end point, so we can understand it as a problem of planting trees. Formula: (120+150+80)/10 = 35.

3. One row has 144 young pioneers practicing, and the other row has 12 people, arranged in a square phalanx. Do you know how many young pioneers are standing around this square?

Analysis: A square has four sides, 12 people have 1 sides, so it is 4×12; There are four corners, so subtract: (1×4).

Formula: (12× 4) —— (1× 4)

= 48-4 = 44 (person)

The mother is 32 years older than her son this year. Three years later, the mother is five times older than her son. How old is her son this year?

Analysis: Follow the trend and guide children to start with the problem. If you want to find your son's age this year, you should first ask his son's age three years ago, and then ask his son's age three years ago. You must know your mother's age three years ago.

Formula: 32+3 = 35; 35÷5=7; 7+3= 10。

1 has three natural numbers, and the results obtained by adding or multiplying them are all the same. What are these three numbers? Analysis: These three numbers are 1, 2 and 3 respectively.

2. The quotient of two natural numbers is 47 and the remainder is 3. The sum of dividend, divisor, quotient and remainder is equal to 629. Do you know what the divisor is?

Analysis: According to the two sentences in the question, 629- remainder-quotient = dividend+divisor; Because dividend-remainder =47 divisors; So you can find the divisor.

Formula: 629—47—3 = 579; (579—3)/48= 12

3. Two natural numbers are subtracted, and the sum of the minuend, the minuend and the difference is 360. Can you find out what a minuet is according to what you have learned?

Analysis: Because: minuend+subtraction+difference =360, minuend = subtraction+difference. So: there are two minuets in 360 degrees. Formula: 360/2= 180

1. In order to praise good people and deeds, Teacher Zhang wants to investigate who did good deeds. He called Xiao Ming, Xiao Gang and Xiao Hua for questioning. Ming said: Xiao Gang did it. Xiaogang said: I didn't do it. Xiaohua said: I didn't do it. Knowing that only one of the three of them told the truth, he asked: Who did this?

Analysis: There are only three cases of this problem, one is done by Xiao Ming, the other is done by Xiao Gang, and the third is done by Xiaohua. Exclusion can be used. If Xiao Ming did it, then Xiao Ming lied, Xiao Gang told the truth, and Xiao Hua told the truth, which contradicted the condition of "only one person told the truth" in the question, so Xiao Ming didn't do it; If Xiao Gang did something good, then Xiao Ming told the truth and Xiao Hua told the truth, which contradicted the condition of "only one person told the truth" in the title, so Xiao Gang didn't do it. If Xiaohua did it, then only Xiaogang is telling the truth. This situation still exists.

Format: Xiaohua did this good thing.

2. If the width of a rectangle is increased by 2cm or the length is increased by 3cm, their areas will all increase by120cm2. What was the area of the original rectangle?

Analysis: If you want the area of the original rectangle, first ask its length and width. It can be known from the figure that its length is equal to 120/2 and its width is 120/3.

Formula:120/2 = 60; 1200/3=40; 60×40=2400。

1, 100 people 200 steamed buns, 4 adults, children 1, and the rest 1. How many adults and children are there?

Analysis: Suppose 100 people are adults and eat 400 steamed buns, which is 400- 199 = 20 1. And every time children are treated as adults, they will eat three more steamed buns, so 20 1/3=67 children are treated as adults. Then adults are 100-67 = 33. The formula is: (4×100—199)/(4—1) = 67.

100—67=33

Of course, it can also be assumed that this 100 person is a child. The logic is the same. You can have a try.

2. A math test paper consists of 24 questions. Deduct 7 points for a correct answer and 5 points for a wrong answer. A student answered 24 questions, but the total score was zero. Do you know how many questions he answered correctly? Suppose the students answered all the questions correctly. . .

Then the score: 24*7= 168 (points)

The actual score is zero, but the score is less: 168-0 = 168 (points).

Answering a wrong question not only won't add points, but will also deduct 5 points, so you will lose money if you answer a wrong question: 7+5= 12 (points).

The wrong question is: 168÷(7+5)= 14 (Tao). The correct question is: 24- 14 = 10 (Tao).

1. During the summer vacation, Xiaoming wants to read a story book. If he reads 12 pages every day, it is estimated that there are still 40 pages left. If you read 16 pages every day, you can finish reading it three days ahead of schedule. How many pages are there in this book?

Analysis: This is a profit and loss problem. Read 16 pages every day. Compared with reading 12 pages every day, you can read more pages at the same time: 16*3+40=88 pages. Because you read four more pages every day, you can get the estimated time.

Formula: 88 divided by 4=22 days. Number of pages in the book: 12*22+40=304 pages. Or: 16 * (22-3) = 304 pages.

2. The sum of the numbers A and B is 540, A minus 120 and B plus 40. At this time, A is exactly three times that of B. How much more is A than B?

Analysis: Now the sum of Party A and Party B is 540- 120+40 = 460.

So now a is 460×3÷(3+ 1)=345, so the original a is 345+ 120=465 B and 540-465 = 75.

So the difference between Party A and Party B is 465-75 = 390.

1, the average of five numbers is 43. If five numbers are arranged from small to large, the average of the first three numbers is 35, and the average of the last three numbers is 50. What's the middle number?

Analysis: the sum of five numbers is 43×5=2 15, and the sum of the first three numbers is 35×3= 105.

The sum of the last three numbers is 50×3= 150.

The first three numbers+the last three numbers =255= the first two numbers+the middle number ×2+ the last two numbers.

The median number is repeated, so the median number is 255-2 15 = 402. Six people each put a bucket in front of the faucet, and the time required to fetch water is 1, 2, 3, 4, 5 and 6 respectively. How to arrange their order of fetching water reasonably, so as to minimize the sum of everyone's queuing time for fetching water? And find the minimum value.

Analysis: The order of fetching water is from small to large. The total time for fetching water is the same, but the waiting time is different. The longer the time for fetching water, the longer the waiting time and the shorter the waiting time.

The minimum value is 6×1+5×+4× 3+3× 4+2× 5+6×1= 56.

1. The fifth-grade students of Yucai Primary School are going to form a square queue to participate in the radio exercise competition. Because there were too many people, one line and one column had to be evacuated, so 29 people were evacuated. How many students are there in Grade Five?

Analysis: A row and a column were evacuated, and 29 people were evacuated. The original team is a square, so the number of people in the original team is equal, but there is a duplicate person in the corner, so the number of people in each team in the original square is1+1= 29+1= 30 (people). * * * There are 15 rows and 15 columns.

Formula: (29+ 1)÷2= 15 (person) 15× 15=225 (person)

2. At the class meeting, the head teacher investigated 54 students in Class 4 (1). In one month, half of the boys did three good things, and the other half did five good things. Half of the girls did six good deeds, and the other half did two good deeds. Calculate, how many good things did the whole class do in a month?

Analysis 1: Half male 3. Half men and half women make eight pieces on average, and half women make six pieces. Half girl 2. On average, every two women made eight pieces, just like men and women, which means that every two people in the class made eight pieces on average. 54 divided by 2 times 8=2 16.

It can also be explained that this problem needs to use the learned concept of "average" to find the average of several numbers, which is actually "moving more to make up less" in the title: "Half of the boys did three good things, and the other half did five good things." Because the figures in the first half and the second half are the same, we can imagine that if a good thing done by the boys in the second half is given to the boys in the first half, then all the boys can be considered to have done four good things. In the same way, the good things that girls do can also be regarded as four good things that all girls do. In this way, we can think that everyone in Class Four (1) has done four good things, 4*54=2 16.

1.A and B two barrels of oil * * * weigh 24 kilograms. Pour the same amount of oil as B into barrel B for the first time, and pour the same amount of oil as A barrel into barrel A for the second time. At this time, there is as much oil in the two barrels. How many kilograms are there in these two barrels of oil?

Analysis: The key to solve the problem is that the oil in barrel A actually doubled after the second pouring of the same amount of oil from barrel B. At this time, a barrel of oil, 24 divided by 2 = 12kg. It shows that when barrel B does not pour oil into barrel A, only 12 divided by 2 = 6 kg in barrel A ... At this time, barrel B oil is twice as much as barrel B oil, and barrel B crude oil: (24-6) divided by 2=9 kg. A barrel originally: 24-9 = 15 kg.

Aunt Wang gave peaches to the children in kindergarten. If each child gets three peaches, there will be 16 peaches. If everyone is divided into five parts, then four parts are missing. How many children are there in this kindergarten? * * * How many peaches are there?

Analysis: This is another profit and loss problem. Compared with splitting peaches twice, each person is divided into five, and each person is divided into three, with a score of * * 16+4=20. This is because everyone gets three, which is 16 more, while everyone gets five. Not only is the extra 16 more, but it is also less. So * * * is 20. Then I thought, if everyone gets two more, how many people get 20 more? 20 divided by 2= 10 people, peaches: 10*2+ 16=46, or: 10 * 5-4 = 46.

3. The students in Class 4 (1) of Hongzhi Primary School have a natural experimental class, with 3 students at each experimental table and 20 more students; Five people sit at each experimental table, which has just been set up. Q * * * How many experimental tables are there? How many students?

Analysis: The idea is the same as the above question. One * * * is 20 people short, and each table is 2 people short. There is a table in * * *: 20 divided by 2= 10. Number of people: 10*3+20=50 people.

1. Students from experimental primary school travel to Yuanmingyuan. If there are 65 people in each car, 15 people can't take the bus. If there are five more people in each car, there will be only one car left. Q * * How many cars are there? How many students are there?

Analysis: (1) If there are five more people in each car. That is, 70 people sit in each car.

(2) the difference between two times is 70+ 15=85 people (3) the difference between each car is 5 people (4)85÷5= 17 (car).

(5) 65× 17+15 =1120 people answer: there are17 cars. There are 1 120 students.

It can also be considered as follows: if there are 65 people in each car and the second number of cars is used (one less than the first one), 65+ 15=80 people cannot be transported. At this time (each car carries 5 people), it is 80÷5= 16 cars. In this way, it can be calculated that the first planned vehicle is 16+ 1= 17 * 65×17+15 =120 people. A: There are 65,438 vehicles.

2. Xiaoming put a total of 103 flags in two boxes, with 12 in the big box and 5 in the small box. And that's it. How many big boxes are there? How many small boxes are there?

Analysis: The four small boxes of the big box 1 1 are mantissas. 103 has a mantissa of 3 and only? 8+? 5 can appear.

The mantissa is 3, (? Numbers indicating vacancies) So 12*4=48, 5* 1 1=55, which adds up to mantissa.

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