First of all, the first question:
First of all, we know that when we meet,
Distance = speed × meeting time
That is 750 km = speed ×3 hours.
Then, the speed sum = 750 ÷ 3 = 250km.
That's easy. Distribute in proportion.
Bus 250÷(3+2)×3= 150 (km)
Freight car 250 (3+2) × 2 =100km
2. Immerse a cylindrical metal casting with a bottom radius of 5cm into a cubic container with a side length of 15cm, and the water surface is 1.57cm higher than the original one. What is the height of this metal casting?
First of all, we know that the cuboid formed by the rising part is the volume of the cylinder we put in.
Then,15×15×1.57 = 353.25 (cubic centimeter).
Divide this volume by the bottom area of the cylinder.
353.25(3. 14×5×5)= 4.5 (cm)
There are three classes in grade six in bright primary school. The number of students in class/kloc-0 is half of that in class 2 and class 3, and the number of students in class 2 is one third of that in class/kloc-0 and class 3. There are 55 students in Class Three. How many students are there in the sixth grade?
X=[(x+55)× half +55]× one third.
Maybe your teacher won't let X go to one end alone.
You can list it like this
X÷ 1/3 =(x+55)× 1/2 +55
3x = half x+82.5
Two and a half x=82.5
x=33
Class one is.
(x+55)× half =(33+55)× half =44 (person)
A * * * is 44+33+55= 132 (person).
Team a and team b jointly build roads. Team B will take eight days to finish if it goes it alone. Now two teams are working at the same time. When it is finished, Team A has finished 7/ 16 of the total length. It is known that the two teams build 9.2 kilometers every day. How many kilometers is this road?
Because he said it was a joint study and there was no rest, B finished it.
1- seven sixteenth = nine sixteenth
It takes eight days to finish, and every day is one eighth.
Nine sixteenth/eighth =4.5 (days)
* * * 4.5 days, 4.5×9.2=4 1.4 (km) per day.
I hope you are satisfied.
Author: recalling the past