1. Demonstration of solving problems in Olympic mathematics in primary schools
1, the school bought football and volleyball, and it took 3 football and 4 volleyball 190 yuan. If you buy six footballs and two volleyballs, you need 230 yuan. How much is a football and a volleyball? Train of thought navigation:
We can extract and compare two purchases:
3 Football +4 Volleyball = 190 yuan (1)
6 Football +2 Volleyballs =230 yuan (2)
We compare (1) and (2), and find that the unit price of football and volleyball cannot be calculated by adding or subtracting two sets of conditions, because there are no same conditions to subtract. Further observation shows that if the formula (1) is expanded twice at the same time, six football and eight volleyball ***380 yuan will be obtained, and then compared with the formula (2), it is found that the number of football is the same, but there are six more volleyballs, which is 380-230 = 150 yuan, that is, six volleyballs are 65438.
Seven "Yellow River" trucks delivered 336 tons of sand in six times. There are 560 tons of sand, which needs to be shipped in five trips. How many more trucks do you need?
Answer and analysis:
Analysis:
If you want to increase the same number of trucks, first ask how many trucks a * * * needs; It is required to transport 560 tons of sand in five trips. How many trucks are needed for each trip? We should know how many tons of sand a truck can carry at a time.
Solution:
How many tons of sand can a truck hold at a time?
336÷6÷7=56÷7=8 (ton)
(2) 560 tons of sand, five trips, how many tons must be transported each trip?
560÷5= 1 12 (ton)
How many more identical trucks do you need?
1 12÷8—7=7 (vehicle)
Column synthesis formula:
560÷5÷(336÷6÷7)—7=7 (vehicle)
We need to add seven identical trucks.
2. Demonstration of problem-solving ability in primary school mathematics Olympics
1. On a bookshelf, there are 52 books on the first floor, 70 books on the second and third floors and 46 books on the fourth floor. How many books are put on each floor on average? 2. Workers in the first and second workshops of a factory 180, workers in the third workshop 103 and workers in the fourth workshop1person. How many people are there in each workshop on average?
There are 43 blue balloons and 43 red balloons, 20 yellow balloons and 33 green balloons in the shop. How many balloons are there on average?
4. Five baskets of tomatoes and two baskets of cucumbers weigh 330 Jin, and three baskets of tomatoes and four baskets of cucumbers weigh 365,438+00 Jin. How much do a basket of tomatoes and cucumbers weigh?
5. Four exercise books and five round pens * * 14 yuan, two exercise books and four ballpoint pens *** 10 yuan. How much is an exercise book and a ballpoint pen?
3. Primary school mathematics Olympic problem-solving ability.
1, find a pattern to fill in the blanks. ( 1)4、9、 16、25、()、()、()
(2) 1、3、6、 10、()、()、()
2. In 1, 2, 3, 99 and 100, the number 2 appears () times in a * * * *.
Xiaoming's distance from home to school is 540 meters, and it takes 9 minutes to go to school. It takes him 3 minutes less to go home than to go to school, so Xiao Ming walks () meters per minute on average.
4, fifth grade math competition, a ***20 questions, answer a question 7 points, answer a wrong question deducted 4 points, Wang Leyan got 74 points, he answered the question correctly ().
5. Mother squirrel picks 24 pine nuts every day in sunny days and 16 in rainy days. She has picked 168 pine nuts for several days, with an average of 2 1 pine nut per day. It has been sunny these days.
6. There is a number plate 3, a number plate 5, a number plate 6 and a number plate 0, which can form () different three digits. The results are in descending order, and the seventh number is ().
7, there is a number divided by 5 times 4 minus 15 plus 35 equals 100, and this number is ().
8.6 lychees weigh as much as 48 apricots, and each apricot weighs 5 grams more than lychees. Each apricot weighs () grams, and each litchi weighs () grams.
9. Two pens and a ballpoint pen * * 16 yuan, one pen and two ballpoint pens * *1/RMB. So a pen is () yuan.
10. The first basket has 170 apples, and the second basket has 250 apples. After giving the first basket () apples in the second basket, there are as many apples in the second basket as in the first basket.
4. The demonstration of the problem-solving ability of Olympic mathematics in primary schools
1, the password of the suitcase is three digits. Xiaoguang said, "It's 954." Xiao Ming said, "It's 358." Xiao Liang said, "It's 2 14." Xiao Qiang said, "Each of you can only guess one number in different positions." The password of this suitcase is (). 2. Wang Fei traveled 240 kilometers at a speed of 40 kilometers per hour, and traveled 60 kilometers per hour on the way back. The average speed of going back and forth in Wang Fei is () kilometers per hour.
A piece of wood is 24 meters long. Saw it into a 3-meter-long section. It takes 6 minutes to saw each section, and * * * takes () minutes.
4, with a 38 cm long wire around the rectangle, so that their length and width are whole centimeters, you can have () kinds of enclosing methods.
5. Every three empty soda bottles in the convenience cold drink shop can be replaced with 1 bottle of soda. Xiaodong bought 99 bottles of soda in the summer vacation, and changed them into empty bottles after drinking, so she can drink () bottles of soda at most.
5. The demonstration of the problem-solving ability of Olympic mathematics in primary schools.
1. It takes 4 hours for Party A and Party B to finish a job, and 5 hours for Party B and Party C.. Now, please ask Party A and Party C to work together for 2 hours, and the remaining Party B needs to work for 6 hours. How many hours does it take to finish the work alone? 2, a project, the first day A to do, the second day B to do, the third day A to do, the fourth day B to do alternately, so it happens to be an integer day to complete; If B does it on the first day, A does it on the second day, B does it on the third day and A does it alternately on the fourth day, then the completion time will be half a day longer than last time. It is known that it takes 17 days for B to do this project alone. A How many days does it take to do this project alone?
Master and apprentice both process the same number of parts. When the master finishes12, the apprentice finishes 120. When the master finished the task, the apprentice finished 4/5 of this batch of parts. How many?
4. A batch of saplings, if distributed to boys and girls, average 6 trees per person; If you plant a single copy for girls, each person will plant 10 trees on average. One for boys, how many trees per person?
A pool is equipped with three water pipes. Tube A is the water inlet pipe, tube B is the water outlet pipe, which can fill the pool water in 20 minutes, and tube C is also the water outlet pipe, which can fill the pool water in 30 minutes. Now, first open the first pipe. When the water in the pool just overflows, it takes 18 minutes to open the second and third pipes. When the first pipe is filled with water, open the second pipe instead of the third one. How many minutes does it take to finish drinking water?