Solution:
According to "the distance between a horse running four steps and a dog running seven steps", it can be assumed that each step of a horse is 7x meters and each step of a dog is 4x meters.
According to "the dog runs five steps, the horse runs three steps", at the same time, the horse runs 3*7x meters = =2 1x meters, and the dog runs 5 * 4x = 20m.
It can be concluded that the speed ratio of horse to dog is 2 1x: 20x = 2 1: 20.
According to "Now the dog has run 30 meters", we can know that the distance between the dog and the horse is 30 meters, and the difference between them is 2 1-20 = 1. Now, what is the distance of 2 1 of a horse, that is, 30 ÷ (2 1-20) × 265438.
2.a train and A train leave from A and B at the same time, and meet 40 kilometers from the midpoint in a few hours? It is known that it takes 8 hours for a car dealership to complete the trip, and it takes 10 hour for a car dealership to complete the trip. How many kilometers is it between A and B?
The answer is 720 kilometers.
According to "the whole journey of car A is 8 hours, and the whole journey of car B is 10 hour", when we met, there were 8 copies of car A 10 and 8 copies of car B (the whole journey 18), and the difference between the two cars was 2 copies. Because the two cars meet at the midpoint of 40 kilometers, it means that the distance difference between the two cars is (40+40) kilometers. So the formula is (40+40) ÷ (10-8) × (10+8) = 720km.
On the 3.600-meter circular runway, two brothers run clockwise from the same starting point at the same time and meet once every 12 minutes. If the speed of two people remains the same and they still start from the original starting point at the same time, and my brother runs counterclockwise, then they meet every 4 minutes. How many minutes does it take them to run once?
The answer is that it takes 6 points 12 points for two people to run a lap.
Solution:
600÷ 12=50, indicating the speed difference between brother and brother.
600÷4= 150, indicating the sum of the speeds of the elder brother and the younger brother.
(50+ 150)÷2= 100, indicating faster speed. The method is to sum a larger number in the difference problem.
(150-50)/2=50, which means the speed is slow. The method is to sum the smaller numbers in the difference problem.
600÷ 100=6 minutes, indicating the time spent by the fastest runner.
600/50= 12 minutes, indicating the time spent by slow runners.
4. The length of the local train 125m, and the speed of the express train 17m per second. The length of the express train is 140m, and the speed is 22m per second. The local train runs ahead and the express train catches up from behind. Then, how long will it take for the express train to catch up with the rear of the local train and completely surpass the local train?
The answer is 53 seconds.
The formula is (140+125) ÷ (22-17) = 53 seconds.
It can be understood that "from catching up with the rear of the local train to completely overtaking the local train" means that the point at the rear of the local train catches up with the point at the front of the local train, so the catching distance should be the sum of the two captains.
On the 300-meter-long circular runway, both parties set off side by side in the same direction at the same time. The average speed of Party A is 5 meters per second, and that of Party B is 4.4 meters per second. How many meters before the starting line did they meet for the first time?
The answer is 100m.
300 ÷ (5-4.4) = 500 seconds, indicating the catch-up time.
5× 500 = 2500m, indicating the distance traveled when A catches up with B..
2500 ÷ 300 = 8 laps ... 100 meters, which means that the total distance of a chase is 8 laps, which is more than 100 meters, which means that we met before the original starting line 100 meters.
6. Alone by the railway. After hearing the whistle of the distant train, 57 seconds later, the train passed in front of her. It is known that the train whistle is at a distance of 1360 meters (the track is straight), and the sound travels 340 meters per second. Find the speed of the train (get the reserved integer).
The answer is 22 meters per second.
Formula:1360 ÷ (1360 ÷ 340+57) ≈ 22m/s.
Key understanding: the car arrives 57 seconds after hearing the sound, which means that the car has already traveled from the place where the sound was made when people heard the sound 1360 ÷ 340 = 4 seconds. That is, it took 4+57 = 6 1.360m * * 0 seconds.
7. The hound found a running hare in front of it at 10 meters away and immediately chased it. The hound took a big step. It ran five steps, and the rabbit ran nine steps, but the rabbit ran very fast. The hound runs two steps, but the rabbit can run three. Ask the hound how many meters it must run to catch up with the rabbit.
The correct answer is that the hound must run at least 60 meters to catch up.
Solution:
From "the hound runs five steps and the rabbit runs nine steps", we can know that for every meter the hound walks, the rabbit walks 5/9 meters. According to "the hound can run 2 steps and the rabbit can run 3 steps", at the same time, the hound can run 2 meters and the rabbit can run 5/9 a * 3 = 5/3 a meters. From this, we can know that the speed ratio between the hound and the rabbit is 2A: 5/3A = 6: 5, that is to say, the hound runs 60 meters and the rabbit runs 50 meters, and the original difference of 10 meter is just used up.
8. In AB, the ratio of time for two people to complete a cycle by bike is 4:5. If two people start exercising from AB at the same time, they will meet after 40 minutes and then move on. How many minutes will B arrive at A later than A arrives at B?
Answer: 18 minutes
Solution: let the whole journey be 1, the speed of a be x, and the speed of b be y.
Column 40x+40y= 1
x:y=5:4
X= 1/72 y= 1/90。
A takes 72 minutes and B takes 90 minutes.
So get the solution.
9. Car A and car B leave relatively from AB at the same time. After the first encounter, the two cars continued to drive and returned immediately after reaching the starting point of the other side. The distance from B to the second meeting is 1/5 of AB's whole journey. It is known that car A traveled 120km when they first met. How many kilometers is AB?
The answer is 300 kilometers.
Solution: Draw a line diagram, and you can know that when two people meet for the first time, they walked 1ab, and from the beginning to the second meeting, they walked 3 AB, so it can be calculated that the distance between A and B is three times that before the first meeting. That is, the distance A * * * walks is 120 * 3 = 360 kilometers. As can be seen from the line chart, A * * * has gone all the way (1+ 1/5).
So 360 ÷ (1+1/5) = 300 km.
It takes 4 hours and 6 hours for two people to ride bicycles from A to B respectively. Now Party A and Party B start from AB and go in opposite directions at the same time. When they meet, they are 2 kilometers away from the midpoint of AB. If two people go to B separately, they will turn back immediately after A ... There is () kilometers between the second meeting point and the first meeting point.
10. It takes 6 hours for a ship to go back and forth at the same speed and go downstream; Countercurrent for 8 hours. If the current speed is 2 kilometers per hour, what is the distance between the two places?
Solution: (1/6-1/8) ÷ 2 =1/48 indicates the fraction of water velocity.
2 ÷ 1/48 = 96 km indicates the total distance.
165438+
Solution:
Meeting is four-seventh of the whole journey, which means that the speed ratio between Party A and Party B is 4: 3.
The time ratio is 3: 4.
So the whole time of the express train is 8/4 * 3 = 6 hours.
6 * 33 =198km
12. Xiaohua travels from A to B, 1 rides, 2/3 rides; Returning from B to A, three-fifths of people rode bicycles and two-fifths rode cars, resulting in a delay of half an hour. It is known that the cycling speed is12km, and the cycling speed is 30km. Q: How many kilometers is it between A and B?
Solution:
Take the distance as 1 and get the time coefficient.
Departure time coefficient: 1/3÷ 12+2/3÷30.
Return time coefficient: 3/5÷ 12+2/5÷30.
The difference between them: (3/5 ÷12+2/5 ÷ 30)-(1/3 ÷12+2/3 ÷ 30) =1/75.
Time to go:1/2× (1/3 ÷12) ÷1/75 and1/2× (2/3 ÷ 30)/kloc-.
Distance:12× [1/2× (1/3 ÷12) ÷1/75]+30× [1/2×
Seeking adoption is a satisfactory answer.