2. A math contest was held in the sixth grade of Yuhong Primary School. There are 28 more girls than boys taking part in the competition. According to the results, all the boys won the prize, while 25% of the girls didn't. The total number of winners is 42, and 5 2 sixth-grade students are known to have participated in the competition. How many students are there?
There are 20 tons more apples than pears in the fruit wholesale department, and pears are 20% less than apples. How many tons of pears are there?
4. Grade 6 students 146, 124 meet the national physical exercise standards. Seek the success rate of this achievement. (Keep one decimal place before the percent sign)
5. A transistor radio, the current price is 165 yuan, which is lower than that of 85 yuan last year by what percentage?
6. Both parties leave from A and B at the same time and meet at 4 o'clock. At this point, Party A walked 40% of the whole journey. The two of them moved on. When b arrives at a, how much does a have to walk to get to b?
7. Due to the improvement of production technology, the time for workers to produce a part is reduced from 12 to 8 minutes. In the past, 40 parts were produced every day. What percentage is the current production efficiency higher than before?
8. Dongxiang planted 450 trees last spring with a survival rate of 80%. Last autumn, the survival rate was 90%. It is known that 65,438+08 trees died last spring than in autumn. How many trees survived in this town last year?
9. A school sent 360 students to summer camp, and it was found that 40% of them were boys.
Boys account for 50%, plus a group of boys. How many boys did you add?
10. A wire is 4.8 meters long. Use 3 1 of the total length for the first time, and use the remaining 60% for the second time. How many meters are left in the end?
1 1. A 2400-meter-long expressway will take 20 days if it is built by the construction team alone; It takes 30 days for Team B to build alone. How many days does it take for the two engineering teams A and B to jointly repair now?
12, a project can be completed by Party A alone in 12 days. After three days' work, Team A has another task, and the rest of the project will be completed by Team B within 15 days. How many days will it take Group B to do this project alone?
13. It takes 12 days for Lao Liu and Xiao Li to do a job together. If Lao Liu is allowed to do it for 8 days, Xiao Li will do the rest of the work alone, and it will take Xiao Li 14 days.
14, Team A and Team B dig canals. Team A completed it in 8 days, and Team B 12 days. Now, after two teams dug for a few days at the same time, team B was transferred, and the remaining team A finished digging in three days. Bravo team dug for a few days.
15. It takes 20 days for Party A and 30 days for Party B to process a batch of parts. Now the two have cooperated to complete the task, and A has rested for 2.5 days in cooperation. B rested for a few days, so *** 14 days was completed. B how many days did you rest?
16, copy a manuscript, the daily work efficiency of A is equal to the sum of the daily work efficiency of B and C; The work efficiency of C is equivalent to1/5 of the daily work efficiency of A and B; If it takes only eight days for three people to cooperate, how many days does it take for B to copy alone?
17, a project, it takes 20 days for Team A to build alone, and 30 days for Team B to build alone. If two teams cooperate, how many days will it take to complete three-quarters of all the work?
18, A traveled from A to B in 2 hours 1/3, and B traveled from B to A in 2 hours 1/2. They set off at the same time and walked in the opposite direction. How many hours did they meet?
19
Party A and Party B can complete a project within 9 88 days. If Party A works alone for 8 days and then works alone for 10 days, how many days will it take for Party A and Party B to complete this project respectively?
20. It takes 12 hours for Party A to complete a project alone. Now Party A and Party B do 2 together.
Hours, the remaining working hours b took 2 15 hours to complete. If all the work is done by B, how many hours will it take to finish?
2 1.a project was completed in 24 hours by one person, and project b was completed in 36 hours by one person. Now it requires 20 hours to complete, and the time for two people to cooperate is as little as possible; How many hours will it take to complete the cooperation between Party A and Party B?
22. To build a road, Team A needs 10 days, Team B needs 12 days, and Team C needs 15 days ... Now Team A and Team B will repair it for four days, and the rest will be repaired by Team C. How many days will it take to complete it?
23. Party A and Party B can complete a project in 8 days, Party B and Party C in 6 days and Party C and Party D in 65,438+02 days. How many days can Party A and Party D work together?
24. For a project, it takes 3 hours for Party A to complete it alone, and 5 hours for Party B to complete it alone.
How many hours does it take people to do 5/4 of this project together?
25. Party A and Party B can process a batch of parts together, and it takes 8 hours to complete the task. If handled separately, it will take 12 hours to complete. Now a,
After two people worked together for 5 2 2 hours, A was transferred out to do other work, and B continued to process 420 parts to complete the task. Ask B.
How many parts have a * * * processed?
26. There are two assignments, A and B. It takes 65,438+00 days for Zhang to complete A alone and 65,438+05 days for Zhang to complete B alone. It takes 8 days for Li to finish work A alone, while it takes 20 days for Li to finish work B alone. If each job can be completed by two people, how many days will it take to complete these two jobs at least?