There is an urgent need for 6th grade Olympiad questions plus 13 answers

How many trees were there in Class A and Class B?

If Class A and Class B take out the same number of trees as Class B and give them to Class B, Class B will also take out the same number of trees from the existing trees and give them to Class A, then both classes will have exactly 28 trees. Q: How many trees were there in each of the two classes?

Answer: There are 35 trees in Class A and 21 trees in Class B.

Analysis: Using the idea of reversibility, if Class B does not give Class A the same number of trees later, Class A should have 28 2 = 14 trees, and Class B has 28 + 14 = 42 trees. If you don't take out the same number of trees from class B at the beginning, the original trees in class B are 42 2 = 21, and the original trees in class A are 14 + 21 = 35.

How long does it take?

There is a chime clock, and every time it is struck, the sound lasts for 3 seconds, and if it is struck 6 times, then it takes a total of 43 seconds from the first strike to the end of the last continuous sound. Now 12 rings, how long does it take from the first knock to the end of the last continuous sound?

Answer: 91 seconds.

Analysis: After each knock, the sound lasts for 3 seconds, so from the 1st to the 6th knock, the total time experienced is 43-3=40 seconds, and there are only 6-1=5 intervals between this, and the time of each interval is 40 5=8 seconds. Now to ring 12 times, you need to go through 11 intervals and 1 3-second duration, which requires a total of :

11 8 + 3 = 91 seconds.

How much money did mom bring?

Mom went to the supermarket to buy laundry detergent, the unit price of Diaopai and Bilang was 8 yuan and 10 yuan respectively, and the money brought by my mother to buy Diao brand laundry detergent can buy 3 bags more than buying Bilang laundry detergent, and there is no money left. Q: How much money did mom bring?

Answer: $120.

Analysis: Because I bought 3 more bags of carved cards, there were 8 3 = 24 yuan more, because Bilang's was 2 yuan more expensive than that of Diaopai, so the number of bags to buy Bilang laundry detergent was 24 2 = 12 bags. In this way, the money brought by the mother is: 10 12 = 120 yuan.

1. The outer diameter of a bicycle tire is meters. If you turn 100 times a minute on average, it takes about a few minutes to cross a bridge 1,155 meters long? (The book.)

2. Use a 10-meter-long rope to circle a tree 3 times, and there are still meters left. What is the approximate centimeter diameter of this tree?

3. There are 120 orchards, than.

20 more, how many percent more?

4. To cut the largest triangle on a semicircular piece of colored paper with a diameter of 2 decimeters, what should be its area?

5. A pair of leather shoes, the original price is 50 yuan, the price will increase by 20% first, and then the price will be reduced by 20%, how much is it now?

6. Happy community.

It is 80%, after investigation, there are 28 households that have not been installed**, how many families are there in the happy community?

7. Xiao Ming read a book, read 20% of the whole book on the first day, read 25% more on the second day than on the first day, and read 12 pages on the third day, which is exactly half of the whole book, how many pages are there in this book?

8. Xinhua Bookstore** A batch of children's books, after 80% of the sales, shipped back 745 copies, so that the existing books are 25 more than the sold, how many children's books are there?

9. The engineering team dug a canal, dug kilometers every day, and dug 70% of the total length in 10 days, how many kilometers are left?

10. If a piece of steel is used, if 1 4 is used, only 9 meters remain. If 40% is used, how many meters are left?

11. A kind of basketball, the original price is 180 yuan, and now it is discounted by 75**. How much cheaper is each?

12. A piece of clothing, 45 yuan cheaper after a 9% discount, how much is the original price of this dress?

13. A shopping mall has a discount**, where you buy goods worth more than 200 yuan, you will receive a 20% discount, so how many yuan worth of goods can you buy with 300 yuan?

14. To produce 240 parts, 25% of which is completed in 5 hours, how many hours will be produced in this way?

15. After Xiaohong collected 24 specimens and sent Xiaofang 4 pieces, Xiaohong had more than Xiaofang 2 3How many specimens did Xiaofang have?

16. Hongqi brand watches were originally priced at 80 yuan each, and now the price is 40% lower than the originalHow much less is each piece sold now?

17. The interest rate of the bank for a fixed term of three years is 5%.If I deposit 30,000 yuan, how much is the pre-tax interest after maturity? How much is the actual interest? Use this one.

What is the maximum amount of dollars he can take?

The question given upstairs. Let me figure it out.

1. There is a clock that is 1 minute slower every hour, and it is aligned at 8 a.m. on March 1, when is the next accurate time?

2. Villages A and B are 10 kilometers apart, and a joint primary school should be built between the two villages. There are 60 people in village A and 40 people in village B. So where should the school be built so that the total trip to school for these 100 students is the shortest?

3. The profit margin of a certain commodity is 20%. If the purchase price is reduced by 20% and the selling price remains the same, what percentage is the profit margin of the goods?

4. Use a rectangular bamboo fence with a length of rice and a width of 2 meters to form a cylindrical grain hoard, the interface is rice, the rice in the grain hoard accounts for 75% of the volume, and it is known that each cubic meter of rice weighs about 1100 kilograms, and how many tons of rice are contained in the grain hoard?

5. What is the sum of the edges of the remaining parts of the largest cube cut off from a rectangle with a length of 8 cm, a width of 7 cm, and a height of 6 cm?

6. There are 100 points in the quadrilateral, and there are a total of 104 points together with the four vertices of the quadrilateral, of which any 3 points are not in a straight line. How many knives do I need to scissors?

7. The length of the fast and slow trains is 150 meters and 200 meters respectively, and they run on parallel tracks in opposite directions, if the person sitting on the slow train sees the fast train passing through the window for 6 seconds, then the person sitting on the fast train sees the slow train passing through the window for how many seconds?

8. The total length of the two ropes is 210 meters, and if the first one increases by 1 3, it will be the same length as the second one; If the second root is reduced by 1 4, it is also the same length as the first. How many meters are each of these two ropes?

9. For a project, it takes 13 days for A, B and C to cooperate. If C takes 2 days off, B has to do 4 more days, or A and B work together for an extra day. How many days does it take for this project to be completed by Person A alone?

10. Fill 105 liters of water into 2 containers, which can fill 1 2 of the first container and the second container, or 1 3Find the capacity of each container.