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2. An elderly couple walked along a circular flower bed with a circumference of 200 meters. They started from the same place and walked back to back. The old lady walks 45 meters per minute and the old man walks 55 meters per minute. How long did it take them to meet for the third time? When we set out, we met for the first time.
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A train must cross the first and second iron bridges at a speed of 600 meters per minute. It takes 5 seconds more to cross the second iron bridge than the first one, and knowing that the length of the second iron bridge is 50 meters shorter than that of the first one, try to find the length of an iron bridge.
Solution:
The bus always runs at a constant speed. When it crosses a 450-long bridge, it takes 33 seconds to get from the upper bridge in front to the lower bridge in the back. When it crossed a 760-meter-long tunnel, its whole body was in the tunnel for 22 seconds. Find the length of the bus.
Solution:
A bus is 200 meters long and a truck is 280 meters long. They travel in opposite directions on parallel tracks. It takes 18 seconds from meeting to leaving the rear of the car. The speed of buses and trucks is 5:3. How many meters do two cars travel per second?
Solution:
6. Someone was walking at a speed of 2 meters per second, and a train came behind him, which took 10 second longer than him. As we all know, this train is 90 meters long. What is the speed of the train?
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7. Captain A is 450 meters long, and B is advancing at a speed of 90 meters per minute. Someone took something from the end of the line to the head of the line and immediately returned to the end of the line at a speed of 3 meters per second. How long does it take to go back and forth?
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8. A team of infantry is advancing at a constant speed of 5.4 km/h, and the correspondent will return to the tail immediately after riding from the tail to the head of the team, which takes 10 minutes in total. If the speed of the correspondent is 2 1.6 km/h, what is the length of the infantry column?
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9. A student team 100 meters, the correspondent is at the end of the team. The team is advancing at a speed of 4 meters per second. When a notice is sent to the head of the queue, the correspondent runs to the head of the queue at a speed of 6 meters per second, and then runs to the end of the queue after the notice is sent. How long did it take for the correspondent to leave and return to the end of the line? (Ignore notification time)
Solution:
10. A bus and a truck are driving in the same direction on parallel tracks. The length of the bus is 200 meters, the length of the truck is 280 meters, the speed ratio of the bus and the truck is 5:3, and the crossing time for the bus to catch up with the truck is 1 minute. What is the speed of each car? If two cars are driving in opposite directions, how long will it take them to cross?
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