1. Party A and Party B cooperate to complete a work. Due to good cooperation, Party A's work efficiency is improved by110, and Party B's work efficiency is improved by 1/5. Party A and Party B cooperate for 6 hours to complete the work, but if Party A does it alone, it needs 165438.
Five students, A, B, C, D and E, stand in a horizontal row with 20 flags in their hands. Now we know that students standing on the right of C * * * hold 1 1 flags, students standing on the left of B * * hold 10 flags, students standing on the left of D * * hold 8 flags, and students standing on the left of E * * hold 16 flags. Who are the five students from left to right? How many flags are there in each?
Xiaoming ran a circle on the 360-meter-long circular runway. It is known that he runs 5 meters per second in the first half and 4 meters per second in the second half. How long did it take him in the second half?
In order to measure the length and speed of the passing train, Xiaoying and Xiaoming brought two stopwatches. Xiaoying used one watch to record the train passing in front of him for 15 seconds, and Xiaoming used another watch to record the train passing from the first telephone pole in front and the second telephone pole in the back for 18 seconds. Knowing that the distance between two telephone poles is 60 meters, we can find out the total length and speed of the train.
Xiaoming walks from home to school in the first half and rides a bike in the second half. Go home from school, take the bus for the first time 1/3, and walk for the second time 2/3. As a result, I spent 20 minutes more time at school than at home. How many kilometers is Xiaoming's distance from home to school?
2. The eighth grade Olympic math puzzle II
1. There is a batch of rice in the grain depot. For the first time, half of the total rice was shipped out of 3 tons, and for the second time, the remaining half was shipped out of 5 tons, leaving 4 tons. How many tons of raw rice is in the grain depot?
2. Dad bought some oranges. On the first day, the whole family ate more than half of these oranges. I ate more than half the next day and more than half the third day, leaving 1. How many oranges did dad buy?
3. A shopping center sells computers. More than half of the total 10 computers were sold in the morning, and more than half of the remaining 10 computers were sold in the afternoon, leaving 50 computers. How many computers are there in this shopping center?
4. Department stores sell washing machines. In the morning, they sold more than 20 washing machines. In the afternoon, they sold more than half of the remaining 15, leaving 75 washing machines. How many washing machines are there in the shop?
5.A car goes from A to B, and when it reaches the whole journey, it is still 400 kilometers away from B. It is known that it takes 8 hours for this car to complete the journey. What is the average speed of this car?
3. The eighth grade Olympic math puzzle, the third part
1. The fast clock is faster than the standard time 1 min, and the slow clock is 2 minutes slower than the standard time. If two clocks are adjusted to the standard time at the same time, the result is that within 24 hours, the fast clock shows 9 o'clock sharp and the slow clock shows 8 o'clock sharp. What is the standard time at this time? When were these two clocks set at the same time?
2. A scientist designed a strange clock. Its day and night have 10 hour and each hour has 100 minute (pictured). When this clock shows 5 o'clock sharp, it is actually 12 noon sharp. When this clock shows 3: 75, what time is it actually? What time does this clock show at 5: 24 pm?
Uncle Li is going to work in the factory at 3 pm. He estimated that it was almost time for work, so he went to look at the clock at home, and the clock stopped at 12: 08 10. He quickly wound the clock and forgot to set his watch in his hurry. When he arrived at the factory, he saw that there were still 10 minutes to go to work. At night, it is 165438+.
4. It takes 13.6 yuan to buy 2.5 kilograms of apples and 2 kilograms of oranges. As we all know, a kilogram of apples is more expensive than a kilogram of oranges. What is the unit price of these two fruits?
5.24 yuan for 4 pens and 9 ballpoint pens. It is understood that two pens can buy three ballpoint pens. How much are these two pens?
4. The fourth volume of the eighth grade Olympic mathematical puzzle
1. The number of chickens in Helin's family is six times that of geese. There are eight geese and 15 ducks in Abby Mallard. How many chickens does He Lin have?
Xiao Min bought a book and a bag of sweets. It costs 3.60 yuan to buy a book, and the money spent on sugar is five times as much as that on books. How much money does she have left in 50 yuan?
Xiaofeng went to the teacher's house to visit the teacher. If you go back and forth by bike, you need to use 1: 20 on the way. If you ride a bike when you go and walk when you come back, it will be 2: 30. How long does it take Xiaofeng to walk back?
4. Two cars, A and B, start from the same station and drive in opposite directions, and drive for 360 kilometers at 3: 00. The speed of A is twice that of B. What are the speeds of A and B respectively?
A, B and C each have several peaches. After A gave B 2 peaches, B gave C 3 peaches, and C gave A 5 peaches, all three people had 9 peaches. How many peaches are there in A, B and C?
5. The eighth grade Olympic math puzzle, chapter 5.
1, Xiaoyun walks from home to the store at a speed of 40 meters per minute. Five minutes later, Xiaoying caught up with Xiaoyun. She caught up with Xiaoyun 600 meters away from home. What is Xiaoying's speed?
2. A group of middle school students went to a certain place for military training. They are advancing at a speed of 5 kilometers per hour. After walking for 6 hours, the school sent Mr. Qin to catch up with the students by bike at a speed of 15 km/h to convey the school notice. How many hours can Teacher Qin catch up with the team? How many roads did the motorcade walk when it caught up?
Xiaoming walks to school, walking 70 meters every minute. After leaving home 12 minutes, my father found Xiao Ming's pencil case at home, and immediately rode to find Xiao Ming at a speed of 280 meters per minute. So how many minutes after his father left, he caught up with Xiao Ming?
The circular runway is 400 meters long. Xiao Qiang runs 300 meters per minute, and Xiao Xing runs 250 meters per minute. Two people set out for the same place and the same direction at the same time. How long did it take Xiao Qiang to catch up with Xiaoxing for the first time?
On a 300-meter-long circular runway, Party A and Party B start from the same point and run in the same direction. Party A runs 9 meters per second and Party B runs 7 meters per second. Now Party B is 100 meters behind Party A. Q: How long will it take Party A to catch up with Party B?