Primary School Mathematics Proportions Questions, Primary School Mathematics About Proportions

First of all, it is important to know that the arrival of students from both teams at the same time implies that both teams of A and B have the same walking distance. Second, the time it takes for the team to arrive is equal to the time the car is running.

It's a bit difficult from an elementary school perspective.

Let the whole journey be 1, and the walking distance of Team A is x.

1-x)/40+x/4=(1-x)/40+(1-x)/40+(1-2x)/50

x = 1 7 is better than 1 7

If the whole journey is 1, and the walking distance of team A is x, then there are (1-x) 40+x 4=(1-x) 40+(1-x) 40+(1-2x) 50, x=1 7, and the ratio is 1 7

Cheating! No way! No! Otherwise, I'm the one who harmed you and didn't learn the knowledge!

Assuming that the car returns to pick up the students of team B immediately after driving for t hours, the distance traveled by team A is 40t, the distance traveled by team B is 4t, and the distance between the two teams is 40t - 4t = 36t.

Now the empty car goes to pick up team B at a speed of 50 kilometers and team B also arrives at a speed of 4 kilometers and hours, and the time taken is 36t (50 + 4) = t*2 3, then the distance traveled forward by team A is 4 * t * 2 3 = t * 8 3, and the distance between teams A and B is still 36 t at this time.

After team B met the car, they began to chase team A, and the time taken was 36t (40 - 4)=t, and when they caught up, they also reached the end point, at which time team A drove 4t forward.

Therefore, the whole journey = the distance of team A by car + the distance of team A walking.

40t + t*8/3 + 4t=40t + t*20/3=t*140/3

Then the ratio of the walking distance of the students of team A to the whole course is: t*20 3 to t*140 3=1:7

If Team A takes S kilometers, it takes S 40 hours.

At this time, B has walked s 40 4=s 10 km.

A gets off the bus and is 9s 10 kilometers away from B.

The time when the car returns to meet B.

9s 10 (50+4) = s 60 hours.

In this way, B has gone forward again s 60 4 = s 15 km.

Similarly, A also walked 15 km.

The time it takes for B to catch up with A in the car.

9s 10 (40-4) = s 40 hours.

In this way, A travels another 40 4=s 10 km.

So, A walked s 15 + s 10 = s 6 km.

A travels S kilometers by car.

The ratio of the walking distance of the students of Team A to the whole journey is the same.

s/6:(s/6+s）=1:7

This is the sixth grade Olympiad topic: travel problems.

Solution: If you drive for x hours, you will travel 40x kilometers.

From the starting point to the car to pick up the students of Team B, it is actually the car that is doing an encounter problem with the students of Team B, and the encounter distance is 2 40x kilometers. Also, the time when Team A takes the car is the time when Team B walks, and the time when Team B takes the car is the time when Team A walks, so it is not OK!!

Because the front potato is 3 times the bottom of the bottom is 3 times the bottom of the bottom, so it is 3:1 than the waiter, which means that the bottom is 2 more than the bottom of the bottom, and the bottom is 6cm, because the parallelogram is equal to the opposite side, so the bottom is 6cm more than the top 6cm is 2 parts, that part is 6 divided by 2 = 3cm one, the top bottom is 3 parts, the bottom is 1 part, the total is 4 parts, 3 4 is the bottom and the bottom of the sum of the talker.

1. If 12a 7b, then the ratio of a to b is (

If a, b (

a：b=7:12

b = 62, if 1/2 x 2/3y, then x and y (choice: proportional, inversely proportional, disproportionate, undecidable).

Because x:y=2 3:1 2=4 3

So x and y are directly proportional.

3. The students donated money to the children's welfare home, and the ratio of money between the first and second classes of the sixth grade was 7 to 8, and later the 61 class donated 50 yuan, and the amount of money donated by the 61 class accounted for 60% of the total donations of the two classes. How much did the two classes donate?

It turns out that the first class of the sixth grade accounts for 7 (7 + 8) = 7 15 of the total donations of the two classes: 50 (60%-7 15) = 375 yuan 4, on the map with a scale of 1 to 3,000,000, the distance between a and b is measured by centimeters. If a truck departs from place A at 8 a.m., 9:48 a.m

When it arrives at point B, how many kilometers does this truck travel per hour on average?

Actual distance: 3000000) = 7200000 cm = 72 km 9:48 - 8 hours = 1 hour 48 minutes = hours.

Average travel per hour: 72 km.

Question 1: You can choose these four numbers to form eight proportions, or you can choose these four numbers to form eight proportions, so there are 16 proportions in total.

Question 2: The two inner terms are reciprocal to each other, that is, the product of the two inner terms is 1, so the product of the two outer terms is also 1, so the other outer term is two-fifths.

1. Determine whether the two quantities in the following questions are proportional? In what ratio, write the relationship 1, the class size is fixed, the number of attendees and the number of absences. Number of attendees + number of absences = disproportionate class size.

2. The first term of the ratio must be fixed, and the latter term of the ratio is the ratio. The ratio of the latter term = the former term, certainly, inversely proportional. 2. Judgment.

1. The class size is fixed, and the number of attendees is inversely proportional to the attendance rate. ( Number of attendees Attendance = class size, proportional.) 2. The radius of the bottom surface of the cylinder is fixed, and the volume is proportional to the height.

Volume = radius squared High volume High = square of radius, certain 3, oil yield is certain, soybean tonnage is inversely proportional to soybean oil tonnage. ( Tons of soybean oil Tons of soybeans = oil yield.) 4. The circumference of the circle is fixed, and the radius of the circle is inversely proportional to pi.

2 Pi Radius = Perimeter Pi Radius = Perimeter x = 8y (x and y are not 0), x is proportional to y. ( x y=8 76, the subtraction is certain, and the subtraction is not proportional to the difference.) ( Minus + difference = subtracted, disproportionate 7, the number of revolutions of the wheel is inversely proportional to the distance.)

The number of revolutions = the circumference of the wheel, proportional to 8, the outer diameter of the bicycle is certain, and the distance traveled is proportional to the number of revolutions of the wheel. ( Distance Number of revolutions = Perimeter = Outer Diameter, certain.)

Look at the number of people in two classes as a whole, that is, the unit "1".

Originally, 1 shift accounted for 8 15, and after 8 people were transferred, it accounted for 4 9, a decrease of 8 15-4 9 = 4 45

That is to say, 4 45 of the total number of students in the two classes is 8 people, and the total number of students is: 8 4 45 = (90 people).

Class 61: 90*8 15=48 (person).

Class 62: 90*7 15=42 (person).

1. (1) Disproportionate, class size = number of attendees + number of absentees (2) proportional, the former term = the latter term multiplied by the ratio, and the ratio is proportional to the latter item. 2. (1) False: Disproportionate, class size = number of attendees + number of absentees (2) True:

Volume = base area multiplied by height (3) False: proportional. Oil yield = tons of soybean oil divided by tons of soybeans (4) pairs:

Circumference = 2 times radius multiplied by pi (5) true (6) false: there is no proportional relationship (7) false, the previous condition? (8) Correct.

Look at the number of people in two classes as a whole, that is, the unit "1".

Originally, 1 shift accounted for 8 15, and after 8 people were transferred, it accounted for 4 9, a decrease of 8 15-4 9 = 4 45

That is to say, 4 45 of the total number of students in the two classes is 8 people, and the total number of students is: 8 4 45 = (90 people).

Class 61: 90*8 15=48 (person).

Class 62: 90*7 15=42 (person).

2×8÷【8/（8+7） －4/（4+5）】=16÷（8/15－4/9）

180 (person).

Class 1: 180 8 (8+7)=180 8 15=96 (person) Class 2: 180 7 (8+7)=84 (person).

It's better to change the form of the score there, and use the score line, so you don't have to put so many brackets.

Solution: If there are 8x people in class 61, then class 62 has 7x

8x-8):7x=4:5

40x-40=32x

8x=40x=5, so there are 8x=8*5=40 (people) in class 61, and 7x=7*5=35 (people) in class 62

Equation Method:

Solution: If there are x people in the class, then there will be (7 8x) people in the class.

x-8):(7/8x+8）=4: 5

5(x-8)=4（7/8x+8）

5x-40=

x=48When x=48, 7 8x=7 8x48=42 (person) arithmetic:

8 [(8 8+7)-(4 4+5)] = 8 [4 45] = 9090 (4 + 5) * 4 + 8 = 48 (person).

90 (4+5)*5-8=42 (person).

A: There are 42 students in Class 61 and 48 students in Class 62.

Solution: If there are x people in class 61, there will be x people in class 62.

1）(x-8):(7/8x+8）=4: 55(x-8)=4（7/8x+8）

5x-40=

x=482)7 8x=7 8x48=42 (person).

A: There are 42 students in Class 61 and 48 students in Class 62.

If there are 8x people in class 61 and 7x people in class 62, then (8x-8):(7x+8)=4:5, and the solution is: x=6, so class 61 has 8x=48 people, and class 62 has 7x=42 people.

1 shift is 8x, 2 shift is 7x. (8x-8) (7x+8)=4 5, solution: x=6. So, there are 48 people in Class 1 and 42 people in Class 2.

According to the question, the total number of grades remains the same, the previous class is 8 (7+8) of the total number of students, the second class is 7 (7+8), the first class after the transfer is 4 (4+5) of the total number, the second class is 5 (4+5), and 8 people is the difference between each class before and after the transfer, with 8 (8 (7 + 8) -4 (4 + 5)) = 90, 90 is the number of the whole grade, and then the number of people in the first class and the second class can be calculated through proportional distribution.

There are X people in class 61 and Y people in class 62.

x:y=8:7, so 7x=8y

x-8:y+8=4:5, so 5(x-8)=4(y+8) is solved to x=48, y=42

Class 61 is 48 students. Class 62 is 42 people.

Question 1: You can choose these four numbers to form eight proportions, or you can choose these four numbers to form eight proportions, so there are 16 proportions in total.

Question 2: The two inner terms are reciprocal to each other, that is, the product of the two inner terms is 1, so the product of the two outer terms is also 1, so the other outer term is two-fifths.

1. If 12a 7b, then the ratio of a to b is ( ) if a , b (

a：b=7:12 b=6

2. If 1/2 x 2/3y, then x and y (choice: proportional, inversely proportional, disproportionate, undecidable).

Because x:y=2 3:1 2=4 3 so x and y are proportional.

3. The students donated money to the children's welfare home, and the ratio of money between the first and second classes of the sixth grade was 7 to 8, and later the 61 class donated 50 yuan, and the amount of money donated by the 61 class accounted for 60% of the total donations of the two classes. How much did the two classes donate?

It turns out that the first class of the sixth grade accounts for 7 (7+8) = 7 15 of the total donations of the two classes

Total donation for two shifts: 50 (60%-7 15)=375 yuan.

4. On a map with a scale of 1:3,000,000, measure a and b to be centimeters apart. If a truck departs from A at 8 a.m. and arrives at B at 9:48 a.m., how many kilometers does the truck travel on average per hour?

Actual distance: 3000000) = 7200000 cm = 72 km.

9:48 a.m. - 8 a.m. = 1 hour 48 minutes = hours.

Average travel per hour: 72 km.

：12；b = 6 2, proportional to kilometers of hours.