2. Lingyan Mountain height 1 km. It takes Mr. Chen 40 minutes to climb the mountain and only half an hour to descend it. Find the average speed of going up and down the mountain.
3. Tortoise and Rabbit Race, the whole distance is 2000 meters. The tortoise climbs 20 meters per minute and the rabbit runs 250 meters per minute. The proud rabbit slept on the road and woke up to find that the tortoise had reached the finish line, and he was still 250 meters away from the finish line. How many minutes did the rabbit sleep?
4. It takes 4 hours for a car to drive from A to B, and 6 hours for a truck to drive from B. The two cars start from A and B at the same time and meet at a distance of 24 kilometers. How many kilometers is it between A and B?
Xiaoming lives away from school1.2km. He walks to school every day. If you run 60 meters per minute, you will be 2 minutes late. If he wants to arrive three minutes before class, how many meters does he have to walk every minute?
6. Bicycle tires are scrapped when the front wheels are installed for 4000 kilometers. If installed on the rear wheel, it can only travel 3000 kilometers. Travel as far as possible. How many kilometers can a pair of tires mounted on a bicycle travel after a certain distance if the front and rear tires are interchanged? (Numbers are reserved as integers)
7. As shown on the left, the small circle is inside the big circle, and the two circles have a common point A. Two ants start from point A at the same speed and crawl on the big and small circles at the same speed according to the direction indicated by the arrow. It is known that the diameters of two circles are 32 cm and 20 cm respectively. Q: When the ants on the small circle crawl several times (back to point A), are the two ants the farthest apart?
8. After school, Xiao Qiang walked south along Renmin Road at a speed of 60 meters per minute. Every 10 minutes along the way, a 1 bus overtook him from behind, and every 8 minutes, another oncoming 1 bus was encountered. If 1 bus runs at the same speed at equal intervals, what is the departure time interval of 1 bus?
I hope I can help you O(∩_∩)O