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Mathematical problems (percentage)
Mathematical examples

1. A convoy delivered a batch of goods. 20% of the total was delivered on the first day. The ratio of the first day to the second day is 3: 2, leaving 520 tons. How many tons were there in this shipment?

2. The distance between Party A and Party B is 865,438+00 kilometers, and the bus and train start from both places at the same time. Bus travel 18 hours, truck travel 27 hours. How many kilometers did the cars meet?

3. Dingding and Ningning each have a box of chess pieces, and there are 270 pieces in two boxes. Dingding gave her 25%. Ningning's chess pieces have just increased by 20%. How many pieces do they each have?

4. Add 10 kg of water to the salt water with a concentration of 20% to become the salt water with a concentration of 16%. How many kilograms was the original salt water?

5. Party A's deposit 1800 yuan. If Party A withdraws 40% of his deposit and Party B withdraws 200 yuan, it means that the deposits of two people are equal. How much did Party A and Party B originally save?

6. A commodity is priced at a profit of 20%, and then 20% off, resulting in a loss of 64 yuan. What is the cost of this commodity?

8. Children in kindergarten share cookies. If everyone divides 5 yuan, there will be 22 yuan left. If each person is divided into 7 pieces, there will be less 18 pieces. How many children are there in kindergarten? How many cookies are there in a * * *?

8. Xiaoming practices the 3000-meter race. If the speed is increased by 25%, how much time will be shortened?

9. There are 270 eggs in the two baskets of Party A and Party B. If 30 eggs are taken from Party A, the two baskets are the same. What is the percentage of Party A's original basket?

10. There is a barrel of oil, 40% of which is taken out for the first time, and the amount taken out for the second time is less than that for the first time 12kg. There are still 28 Jin in the bucket. How much is this barrel of oil?

1 1. For a rectangular blackboard, its length and width increase by 10% respectively, and what percentage does its area increase?

12. A rectangular vegetable field with one side against the wall and the rest surrounded by a 44-meter fence. As we all know, the length-width ratio is 5: 3. What is the area of this field?

13. There is a glass of salt water, and the ratio of salt to water is 1: 10. Then add 2 grams of salt. What is the ratio of salt to water in new brine?

14. Party A and Party B start from Party A and Party B at the same time and move in opposite directions. Line A 15km/ h, after the two meet, A walks for 2 hours to reach B, and B walks for 45km to reach A, OK? Kilometers per hour?

15. Digging a canal, 20% of the total length was dug in the first week and 3/8 of the total length was dug in the second week. At this time, the midpoint120m has been exceeded. How long is this canal?

16.4. Two cars, A and B, travel in opposite directions from two places, with a distance of 5 16 km. After six hours, the repair of the second car was suspended. At this time, the distance between the two cars is 72 kilometers. Two hours later, the first car kept its original speed and met the second car. Find the speed of car B.

17.( 1) Grade five students take part in the composition competition. The average score of the top four students is 84.5, the average score of the 456 students is 6.5 points lower than that of the top four students, and the average score of the top six students is 82 points. What's the score of the fourth student?

18. Forty-five students in a class took the final exam. After the results were announced, 10 students got full marks in mathematics, 3 students got full marks in mathematics and Chinese, and 29 students got no full marks in both subjects. So how many people got full marks in Chinese?

19. This store sold 1026 rice cloth in three days. The sales volume of the second day is twice that of the first day; On the third day, it sold three times as much as the next day. How much rice cloth do you want to sell in three days?

20. Two cars, A and B, travel in opposite directions from the midpoint of the East Village and the West Village at the same time. Six hours later, the A bus arrived in the East Village, and the B bus was 42 kilometers away from the West Village. As we all know, the speed of car A is twice that of car B ... How many kilometers is the highway between East and West villages?