Solution: velocity b = 52×1.5 = 78 km/h.
325/(52+78)=325/ 130=2.5.
2 1, two cars, Party A and Party B, start from A and B at the same time and drive in opposite directions. A travels 80 kilometers per hour, and B travels 10% of the whole journey per hour. When B travels to 5/8 of the whole journey, Party A can reach B through 65438+ 0/6 of the whole journey. How many kilometers is it between A and B?
Solution: 5/8 of the whole journey of Bank B = (5/8)/(110) = 25/4 hours.
AB distance = (80× 25/4)/(1-kloc-0//6) = 500× 6/5 = 600 km.
22. Two cars of Party A and Party B leave the two places relatively at the same time. Car A travels 40 kilometers per hour and car B travels 45 kilometers per hour. When the two cars meet, the second car is 20 kilometers away from the midpoint. How many kilometers are the two places apart?
Solution: The speed ratio of A and B = 40: 45 = 8: 9.
Distance ratio between Party A and Party B = 8: 9.
When meeting, Party B made the whole journey of 9/ 17.
Then the distance between the two places = 20/(9/17-1/2) = 20/(1/34) = 680km.
23. Party A and Party B walk in opposite directions in two places at the same time, and meet at E. Party A continues to walk at B. Party B takes a rest 14 minutes, and then continues to walk at A. Party A and Party B turn back immediately after arriving at B and A respectively, and still meet at E. Know that A walks 60 meters per minute, B walks 80 meters per minute, and how many meters are there between A and B.
Solution: treat the whole process as a unit 1.
The speed ratio between Party A and Party B is 60: 80 = 3: 4.
The distance a of point E is 3/7 of the whole journey.
When we meet for the second time, one * * * is three times.
After resting 14 minutes, A walked 60× 14=840 meters.
After the first meeting, B left 3/7×2=6/7.
Then the distance traveled by A is 6/7×3/4=9/ 14.
In fact, A left 4/7×2=8/7.
Then during B's rest, A left 8/7-9/ 14= 1/2.
Then the whole journey = 840/( 1/2) = 1680m.
24. Two trains, A and B, leave relatively from AB at the same time. When they meet, the distance ratio between A and B is 4: 5. It is known that train B travels 72 kilometers per hour, and it takes 10 hour for train A to complete the whole journey. How many kilometers are there between AB and AB?
Solution: The ratio of the distance left when meeting is 4: 5.
Then the distance ratio is 5: 4.
The time ratio is equal to the inverse ratio of the distance ratio.
Distance ratio between Party A and Party B = 5: 4.
The time ratio is 4: 5.
Then it takes 10×5/4 = 12.5 hours for line B to complete the journey.
Then AB distance =72× 12.5=900 km.
8. For a project, the time for Party B to complete the project alone is twice that of Party A's team; It takes 20 days for Team A and Team B to cooperate to complete the project. The daily work cost of Team A is 1 1,000 yuan, and Team B is 550 yuan. From the above information, which company should I choose from the perspective of saving money? How much should be paid to the construction team?
Solution: The sum of the work efficiency of both parties = 1/20.
Working time ratio of Party A and Party B = 1: 2.
Then the work efficiency ratio of Party A and Party B is 2: 1.
So the working efficiency A = 1/20×2/3= 1/30.
Party B's work efficiency =1/20×1/3 =1/60.
A it takes one person 1/( 1/30)=30 days.
B It takes1(1/60) = 60 days to complete it alone.
A need to complete it alone1000× 30 = 30,000 yuan.
B alone needs 550× 60 = 33,000 yuan.
The cooperation needs of Party A and Party B are (1000+550) × 20 = 31000 yuan.
obviously
A needs the least money to finish it alone.
Choose a, you need to pay 30000 yuan for this project.
9. For a batch of parts, if Party A and Party B work together for 5.5 days, it can exceed 0. 1 of the batch of parts. Now Party A works for 2 days, then Party A cooperates for 2 days, and finally Party B works for 4 days to complete the task. If Party B works alone, how many days can this batch of parts be completed?
Solution: treat all parts as a unit 1.
Then the sum of the work efficiency of Party A and Party B = (1+0.1)/5.5 =1/5.
The whole process is that A works 2+2=4 days.
B working 2+4=6 days.
It is equivalent to 4 days of cooperation between Party A and Party B, and 1/5×4=4/5 is completed.
Then B does it alone for 6-4=2 days 1-4/5= 1/5.
So it takes 2/( 1/5)= 10 days for B to complete it alone.
for reference only