It seems complicated to solve this problem, but I read the answers of several heroes upstairs, right.
The third grade of primary school
For students, this is a heavenly book. Actually, the problem is very simple.
First of all, if you like.
The first batch of students
Send them directly to the factory, and then pick up others when they come back, so the first group of people will have to wait in the factory, so make full use of the waiting time, put the first group in the right place, and then walk to pick up others when they come back.
The last group of people
When they arrived at the factory, except for the last group of people, they all just arrived at the factory.
Secondly, therefore, the whole process is the sum of the time taken by the car to send the first group of people to the right place and the time taken by the first group of people to walk from point C to the factory.
Determine the point C again, because the speed of the car is 45 km/h and the speed of the person is 5 km/h, so the efficiency of the car is 9 times that of the person, so the point C should be 90% of the whole journey, that is, at 27KM.
Finally, the total time is 27/45+(30-27)/5 = 6/5 hours, that is, 1.2 hours, that is, 1 hour 12 minutes.
Ranch * * * has
Good guys and bad guys
35,665,438+0. Later, 60 sheep were sold and 65,438+000 goats were bought. Now there are 1 goat in Mianyang, which is twice that of Mianyang.
The number of goats is 1 and the number of sheep is 2+ 1.
Now goats have: (3561-60+100-1) ÷ (1+2) =.
1200 (only)
The original goat is1200-100 =1100 (only).
Original sheep: 3561-1100 = 2461(only).