Solution: AB distance = (4.5× 5)/(5/11) = 49.5 km.
2. A bus and a truck leave from Party A and Party B at the same time. The speed of a truck is four-fifths that of a bus. After a quarter of the journey, the truck and the bus met for 28 kilometers. How many kilometers is it between A and B?
Solution: The speed ratio of passenger cars and trucks is 5: 4.
Then the distance ratio when meeting is 5: 4.
When they met, it was 4/9 of the whole truck journey.
At this time, the truck has traveled all the way 1/4.
4/9- 1/4=7/36 from the meeting point.
Then the whole journey = 28/(7/36) = 144km.
3. Party A and Party B walk around the city, with Party A walking 8 kilometers per hour and Party B walking 6 kilometers per hour. Now both of them start from the same place at the same time. After B meets A, it will take another 4 hours to return to the original starting point. B How long does it take to go around the city?
Solution: The speed ratio of A and B = 8: 6 = 4: 3.
When they met, B walked 3/7 of the way.
Then 4 hours is 4/7 of the whole trip.
Therefore, the time spent on line B in a week =4/(4/7)=7 hours.
4. Party A and Party B walk from place A to place B at the same time. When Party A completes the whole journey of 1\4, Party B is still 640 meters away from B. When Party A completes the remaining 5\6, Party B completes the whole journey of 7\ 10. What's the distance between AB and place?
Solution: After A left 1/4, the remaining 1- 1/4=3/4.
Then the remaining 5/6 is 3/4×5/6=5/8.
At this time, a * * * left 1/4+5/8=7/8.
Then the distance ratio between Party A and Party B is 7/8: 7/ 10 = 5: 4.
So when A goes 1/4, B goes 1/4×4/5= 1/5.
Then AB distance =640/( 1- 1/5)=800 meters.
5. Two cars, A and B, start from A and B at the same time and drive in opposite directions. Car A travels 75 kilometers per hour, and it takes 7 hours for car B to complete the journey. Three hours after the departure of the two cars, the distance is15km. What is the distance between a and b?
Solution: Case A: Party A and Party B have not met yet.
3/7 of the 3-hour journey of the B train.
The three-hour journey is 75×3 = 225 kilometers.
AB distance = (225+15)/(1-3/7) = 240/(4/7) = 420km.
In one case, Party A and Party B have met.
(225- 15)/( 1-3/7)= 2 10/(4/7)= 367.5km。
6. One, two people should go this way. A It takes 30 minutes to walk and 20 minutes to walk. After walking for 3 minutes, A found that she didn't take anything, which delayed for 3 minutes. How many minutes does it take to walk from A to B?
Solution: A is 3+3+3=9 minutes later than B.
Think of the whole distance as 1.
Then the speed of a = 1/30.
Speed B = 1/20
When Party A packed up and set out, Party B had already left 1/20×9=9/20.
Then the distance between Party A and Party B is1-9/20 =11/20.
The sum of the speeds of Party A and Party B =1/20+1/30 =112.
Then meet again in (11/20)/(112) = 6.6 minutes.
7. two cars, a and b, start from place a and drive in the same direction. A walks 36 kilometers per hour and B walks 48 kilometers per hour. If car A leaves two hours earlier than car B, how long will it take for car B to catch up with car A?
Solution: distance difference = 36× 2 = 72km.
Speed difference = 48-36 = 12km/h
It takes 72/ 12=6 hours for car b to catch up with car a.
8. Party A and Party B respectively set out from ab, which is 36 kilometers apart, and walked in opposite directions. When Party A departs from A to 1 km, it has been in A until it finds something and returns immediately. After the goods were gone, he immediately went from place A to place B, where Party A and Party B met. He knew that Party A walked 0.5 kilometers more than Party B every hour and asked both of them to walk.
Solution:
A actually walked 36× 1/2+ 1× 2 = 20km when they met.
B walked 36× 1/2 = 18km.
Then A walked 20- 18 = 2km more than B.
Then the meeting time =2/0.5=4 hours.
So A = 20/4 speed = 5 km/h.
Speed B = 5-0.5 = 4.5km/h/h.
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