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A and B are 10 kilometers apart. Now they are going to each other at the speed of 3 km / h and 2 km / h respectively. At the same time, a dog runs from a to B at the speed of 10 km / h. After meeting B, it immediately turns around and runs to a, and then runs to B after meeting a Until Party A and Party B meet, ask for the distance that the dog takes
It takes 10 / (2 + 3) = 2 hours for Party A and Party B to meet, so the dog ran for 2 hours, so the distance the dog walked is equal to 2 * 10 = 20 kilometers
Party A and Party B are walking towards each other on the road with a distance of 6 kilometers, 2 kilometers per hour. Party B walks 4 kilometers per hour, and a dog runs to Party B with a speed of 12 kilometers per hour
I've seen this problem for many times. The dog runs back and forth. We just need to remember that the distance = speed x time, regardless of how many times it runs back and forth. The running time of the dog is the time when two people meet. The meeting time = total distance / speed sum. The problem is solved in this way
6 / (2 + 4) = 6 / 6 = 1, which means that it takes one hour for two people to meet, that is, it takes one hour for the dog to run back and forth
12 x 1 = 12, that's the dog running an hour, the distance is 12 kilometers
3. The speed ratio is 4:5. The distance between the first meeting point and the second meeting point is 400 meters?
Step by step
4 + 5 = 9
The first meeting, a total of 1 line, rabbit line 4
The distance between the first meeting point and a is only 4
For the second meeting, the rabbits were divided into 3 groups, 4 × 3 = 12
The distance between the second meeting point and a is 9 × 2-12 = 6 phr
The difference between the two meeting points is 6-4 = 2
Each 400 △ 2 = 200m
The distance between a and B is 200 × 9 = 1800 meters
The distance between a and B is 2 kilometers. A and B start from a and B at the same time by bike. The speed is 20km / h
The distance between a and B is 2km. A and B start from a and B by bicycle and walk towards each other at the same time. Their speed is 20km / h. If there is a hunting dog running back and forth between a and B at the speed of 30km / h, they will return immediately when they meet. How much distance does the hunting dog pass between a and B?
The hound ran until they met
Therefore, the total running time of hounds is the time when two people meet = 2 (20 + 20) = 1 / 20 hour
So the total distance of hounds is speed × time = 30 × 1 / 20 = 1.5km
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