2. Xiaoming reads a story book. The ratio of pages read on the first day to total pages is 3: 7. If he reads 15 page again, it is just half of the book. How many pages are there in this book?
There are 42 students in the math interest group, 2/7 of whom are girls. Later, several girls were added. At this time, girls accounted for 2/5 of the total number. How many girls did you add?
4. Two baskets of apples * * * 90kg, big basket 1/5, small basket 1/4 * * 20kg. How many kilograms of fruit can the big basket and the small basket hold?
5. A book has 100 pages. After reading 60 pages, how many parts of this book have you read?
6. After cutting off 20% of a rope, connect it to 6m. The result is longer than the original rope1.5m.. How long is this rope?
7. Show me the train tickets for this distance. Children's fare is 25% of adult's fare.
(1) If the adult fare is 12.4 yuan, what is the child fare?
(2) If the child fare is 12.4 yuan, what is the adult fare?
8.( 1), a worker has to process 120 parts, and 80% of them have been processed. How much more to deal with?
A batch of parts in a factory has been processed by 80%, and there are 24 left. How many parts are processed in batches?
There are 20 poplars on campus, and the number of Chinese fir is 60% of that of poplars. How many Chinese fir trees are there?
There are 20 poplars on campus, and the number of Chinese fir is 60% of that of foreign books. How many Chinese fir trees are fewer than poplar trees?
10. After the price of each tape recorder is reduced by 30%, the price is 350 yuan. What is the original price of this tape recorder?
1 1. build a road with 20% of the total length on the first day, 200m on the second day, and the sum of the first two days on the third day. How long is this road?
12. After cutting 20% of a rope, it was connected with 6m, and the result was 30% longer than the original rope. How long is this rope?
13. What percentage of women workers in wool mills are more than men? What is the ratio of male employees to female employees?
14. Due to the improvement of equipment, the daily output of a chemical plant has increased from 40 tons to 60 tons, an increase of several percent?
15. A TV factory produces 4,800 TV sets, of which 4,608 are qualified products, and the qualification rate and rejection rate of TV sets are sought.
16. In an army shooting practice, 100 bullets hit and 25 missed. What's the hit rate?
17. There are 250 employees in the garment factory, and 248 people are on duty today. What's the attendance today? What's the absenteeism rate today?
18. Dissolve 25g of salt in100g of water to find out the salt content of brine.
19. The alloy of tin and lead weighs 45 kilograms, including 27 kilograms of lead. Find out the lead content of this alloy.
20. An expedition originally planned to walk 40 kilometers a day and reach its destination in eight hours. Due to the need of work, it walked 10 kilometers a day, which actually shortened the time by several percent.
2 1. To do the same work, Team A completed it in 4 hours and Team B completed it in 5 hours, so Team A's work efficiency was good.
What's the ratio of team B?
22. A car travels 40 kilometers per hour from A to B, and travels 1000 kilometers per hour when it returns.
M, how much has the speed improved?
23. If a number is increased by 25%, how much percentage should it be reduced to get it back?