![](data:image/svg+xml;utf8,<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 72 71" width="72"></svg>)
The formula of sum difference multiple problem,
The problem of sum and multiple is to find the relationship between the sum of two numbers and the multiple of two numbers
Decimal = sum (multiple + 1)
Large number = sum - decimal or large number = decimal × multiple
Equivalence relation: decimal + decimal × multiple = sum
The problem of difference multiple is to find out the relationship between the difference of two numbers and the multiple of two numbers
Decimal = difference (multiple-1)
Large number = decimal + difference or large number = decimal × multiple
Equivalence relation: decimal × multiple - decimal = difference
The formula of difference multiple problem
Differential multiple problem
Difference (multiple-1) = decimal
Decimals × multiples = large numbers
(or decimal + difference = large)
The formula of circular road travel can be written in 5 to 3 lines
Basic formula: distance = speed × time; distance △ time = speed; distance △ speed = time
Key problem: determine the position during the journey
Encounter problem: speed and X encounter time = encounter distance (please write other formulas)
Encounter problem (straight line): distance of a + distance of B = total distance
Encounter problem (ring): A's distance + B's distance = ring circumference
Pursuit problem: pursuit time = distance difference △ speed difference (write other formulas)
Pursuit problem (straight line): distance difference = distance between pursuer and pursuee = speed difference x pursuit time
Pursuit problem (ring): fast distance - slow distance = circumference of curve
Flow problem: downstream stroke = (ship speed + water speed) × downstream time, upstream stroke = (ship speed water speed) × upstream time
Forward speed = ship speed + water speed, backward speed = ship speed - water speed
Hydrostatic velocity = (downstream velocity + upstream velocity) × 2 water velocity = (downstream velocity - upstream velocity) × 2
Flow problem: the key is to determine the speed of the object, refer to the above formula
Bridge problem: the key is to determine the distance of the object, refer to the above formula
Flow problem = flow velocity + flow velocity △ 2 flow velocity = flow velocity - flow velocity △ 2
An express train and a local train leave from a and B at the same time. When they meet on the way, the distance ratio is 7:5. At this time, the local train runs 70 kilometers less than the express train
How many kilometers per hour does the express train travel?
70 (7 / 12-5 / 12) = 420 km
420 △ 6 = 70 km / h
70 △ 5 / 7 = 98 km / h
The fast train and the local train start from a and B at the same time and run in opposite directions. After driving for a period of time, the two trains meet. The distance from the meeting point to the midpoint of AB is exactly 120 of the total length of ab. the speed ratio of the fast train and the local train is______ ．
(12 + 120): (12 − 120), = 1120:920, = 11:9. A: the speed ratio of fast train to slow train is 11:9
The express train and the local train run from AB for 5 hours at the same time. After meeting, the express train arrives at B for 3 hours. At this time, the local train is 120 kilometers away from a, and the distance of AB is calculated
The express train and the local train run from ab at the same time and meet each other for 5 hours. It can be seen that the two trains travel 1 / 5 of the whole journey every hour
After the meeting, the express arrived at B in three hours. At this time, the two trains made a total of three fifths of the whole journey, so the remaining two fifths of the whole journey
Therefore, AB distance is 120 (1-3 / 5) = 300 km
It takes 8 hours for an express train to go from a to B, and 12 hours for a local train. The two trains are facing each other at the same time. When they meet, the express train runs 48 kilometers more than the local train, so the total distance is calculated
Time ratio: 8 / 12 = 2 / 3
Speed ratio: 3 / 2
48 / (3 / (3 + 2) - 2 / (3 + 2)) = 240 km
It takes 8 hours for an express train to go from station a to station B, and 12 hours for an idle train to go from station B to station a. the two trains leave each other at the same time. When they meet, the express train travels 48 kilometers more than the slow train. How many kilometers are there between station a and station B?
A: the distance between station a and station B is 240 km
The two trains set out from a and B in opposite directions. The slow train takes 8 hours, one third more than the fast train from B to A. when they meet, the fast train takes 48 kilometers more than the slow train to find the distance between a and B
We need to explain
Express time: 8 / (1 + 1 / 3) = 8 / (4 / 3) = 6 hours
The speed ratio of fast train and slow train is the inverse ratio of time ratio, so fast train speed: slow train speed = 8:6 = 4:3
The meeting is that the express takes 4 / (4 + 3) = 4 / 7 of the whole journey, and the local takes 3 / 7 of the whole journey
Distance between a and B = 48 / (4 / 7-3 / 7) = 48 / (1 / 7) = 48 * 7 = 336 km
It takes 8 hours for an express train to go from station a to station B, and 12 hours for an idle train to go from station B to station a. the two trains leave each other at the same time. When they meet, the express train travels 48 kilometers more than the slow train. How many kilometers are there between station a and station B?
A: the distance between station a and station B is 240 km
RELATED INFORMATIONS
- 1. The express and local trains leave from both places at the same time. The express trains travel 33 kilometers per hour. The meeting is four seventh of the whole journey. It is known that it takes 8 hours for the local train to complete the whole journey
- 2. The distance between the two when catching up___________ =The distance between the two at departure
- 3. Is it possible to catch up with the time when the common distance △ speed difference?
- 4. 5 / 6 of a's work efficiency is equivalent to B's work efficiency. Here, the work of () is regarded as unit 1, and the work efficiency of () accounts for 5 / 6?
- 5. To harvest a piece of wheat, it takes 8 hours for a to finish harvesting, and the working efficiency of B is 80% of that of A How many more hours will it take to finish harvesting this piece of wheat?
- 6. How to find the percentage of a number? Can frequency be regarded as the percentage?
- 7. An object begins to slide on the ice surface at a speed of 10m / s, and decelerates evenly. After sliding for 10m, the object stops, so it takes a lot of time for the object to slide for 6m______ S (root is allowed)
- 8. The basic process of solving practical problems with linear equation of one variable generally includes setting, listing and checking, that is (), (), (), (), (), () It's the basis of a series of equations
- 9. Party A and Party B cooperate to complete a work. Due to good cooperation, the work efficiency of Party A is 1 / 10 higher than that of Party A alone, and that of Party B is 1 / 5 higher than that of Party B alone, Party A and Party B work together for 4 hours, completing two fifths of the whole work. The next day, Party B works alone for 4 hours, leaving 13 / 30 of the work unfinished. How many hours does it take for Party A to complete the work alone? Give me a reply in 12 hours!
- 10. (1) It takes 10 days for a job to be completed by Party A alone. If Party A and Party B work together, it takes 6 days. This job will be completed by Party A and Party B after 2 days, and the rest will be completed by Party B alone. How many days does Party B need to work? (2) there is a batch of grain in the warehouse, 2 / 3 of which is less than 1 ton. At this time, the ratio of the remaining grain to the total grain is 3:5?
- 11. What is the length of a circle
- 12. Calculation formula of stirrup length in column
- 13. What is the difference between the waist bar (structural bar) and the torsion bar in the beam
- 14. There may be a formula for calculating the length of spiral reinforcement in pile foundation? For example, the length of spiral reinforcement is Φ 10@12 The diameter of reinforcement cage is 108.4
- 15. How to draw a 400 meter long runway on a 200 meter long and 100 meter wide playground? Draw a nine line diagram
- 16. As shown in the picture, there is a 300 meter small track in the 400 meter track of the school playground. The distance between the large track and the small track is 200 meters. A runs counter clockwise along the large track at the speed of 6 meters per second, and B runs clockwise along the small track at the speed of 4 meters per second. The two start from the intersection a of the two runways at the same time. When they meet on the runway for the second time, how many meters did a run?
- 17. If the curve of the standard 400m runway is semicircle, and the radius of the innermost curve is 36m, and each runway is 1.2 wide, there are six runways 1. What is the radius of the semicircle runway on the outer circle? 2. How many meters ahead of the starting point of the first runner in the 200 meter race? 3. How many meters ahead of the starting point of the third runner in the 400 meter race? 4. If the 400 meter race is still in progress, how many meters ahead of the first runner is the fifth runner?
- 18. Calculation formula of arc length Just answer the formula
- 19. The length or width of the field and equipment on the track and field field is 1.22 meters, except for the width of the track and field, the hurdle frame (springboard)
- 20. The perimeter of the track and field track is 400 meters. The straight part of the track is selected for the 100 meter race. The distance for the athletes to complete the whole race is 400 meters______ And the displacement is______ In the 800 meter race, athletes from different runways complete the whole distance______ (fill in the same or different), displacement______ (fill in the same or different)