Solution: 30 ÷ (110-115),
=30÷ 130,
=900 (pieces);
A: There are 900 parts in this batch.
Comments: This question is based on the total workload "1". According to the relationship between working hours, work efficiency and workload, find out the number corresponding to a fraction of the unit "1", and calculate the quantity of the unit "1" by division.
2; Let Mingming walk 100 m, her father is 100×2-20= 180, she is twice as old as her mother, and 40 is twice as old as her mother, so it is (180+40) ÷ 2 = 65438.
3: 1 minute, 4 cubic meters of water, 1 hour, 240 cubic meters,1hour, 2400 cubic meters. 2400 cubic meters divided by the bottom area: 50×30, which is equal to: 2400÷ 1500= 1.6 meters!
4. Let the unit of package B be "1", then it pours out 1/4, leaving 3/4. Only when 1/2 of package A plus 1/4 of package B equals package B, it means that the weight of package A is only 1/2 of package B, so it is 20.
At this time, chickens and rabbits live in the same cage. Let's assume that they are all from 5 yuan, so the total amount of money is: 5×27= 135 yuan, and the excess is: 135-99=36 yuan, because they are all from 5 yuan, so: 36 ÷ (5-2) = 18.
6. Since the price of chairs is 1/3 of that of tables, four tables are equivalent to 12 chairs, 12+8=20, one ***20 chairs, and 240 ? 20 =12 yuan-chairs.
7. If the length is increased by 2cm, it must be width× height× 2 = 40, then height× width =40÷2=20, and then it is like this: height× length =90÷3=30 length× width =96÷4=24. Since the formula of surface area (rectangle),
10:
8:
Because the speed of bus and truck is 4: 3, the distance ratio of driving in the same time is also 4: 3, which means that the bus travels 1 times more than the truck, 30 kilometers more; So the bus traveled 30× 4 = 120km, so the distance between the two cities is 120x2 = 240km.
Solution: Solution: Because the speed ratio of the two cars is 4: 3,
So the distance ratio between the two cars is 4: 3,
The whole journey is:
30×4×2=240 km.
A: The distance between A and B is 240 kilometers.
Comments: In the trip problem, in the same time, the distance ratio of two cars is equal to the speed ratio of two cars.
9; The first shelf took out 15 books, and the second shelf added 15 books. The gap between them is shortened: 15+ 15=30 copies, while the ratio is 5:8 and the difference is 8-5 = 3. Three books equals 30 books, and one book is: 30 ÷ 3.
10:
Teacher Li dialed 50 points last month.
Suppose miss Li dialed X last month, that's 74-X.
8+0.2X+0. 15(74-X)= 2 1.6
The result is x = 50.
1 1:
Rent five trucks, that is, 5×200= 1000 yuan.
Rent three pickup trucks, which means 3×90=270 yuan.
Total freight: 1000+270= 1270 (yuan
12:* * * The total number of balls is: 2+4=6 black balls, and 2 of them account for 1/3 of the total! The possibility is 1/3.
13: this is also the same cage for chickens and rabbits: sunny and rainy days * * * is: 68/ 14=5.
If it is sunny for 5 days: 5*20= 100.
If it rains completely for 5 days: 5* 12=60.
Let the rainy day be X.
So 68= 100-(20- 12)X
X=4
Similarly, you can also set the sunny day as Y.
So 68=60+(20- 12)y
y= 1
So 65438+ 0 sunny days, 4 rainy days.
References:
The chicken and the rabbit are in the same cage.
14: A+(6/7) x A is the total speed of A and B, which is equal to 468 kilometers divided by 3 hours.
Equation: a+(6/7) x a = 468/3.
So: a = 84, bus speed: 72 km/h, finally done, brother. Take it! ! ! ! ! ! ! ! !
14: supplement: 2 methods:
Suppose the bus speed is V, then the speed is 7/6V, and the topic is (V+7/6V) × 3 = 468.
Unbound v = 72 km/h.