There are 7 people in a tour group. They are going to the railway station by two cars (5 people in each car including the driver). One of them breaks down at a distance of 10km from the railway station. At this time, there are 40 minutes to check in. At this time, the only available car is another car. Assuming that the average speed of the car is 40km / h and the speed of the passenger walking is 4km / h, there are three schemes (1) The car first takes four people to the railway station, the other three people wait in place, and then take the car back to the railway station (2) While the car takes four people to the railway station, the other three people walk first and then take the car back to the station (3) The car first takes four people to an underground car and returns. These four people walk to the station, while the other three people walk first and then take the car back to the station, and two groups of people arrive at the railway station at the same time Through calculation to determine whether these three schemes are feasible, if feasible, which scheme takes time?

There are 7 people in a tour group. They are going to the railway station by two cars (5 people in each car including the driver). One of them breaks down at a distance of 10km from the railway station. At this time, there are 40 minutes to check in. At this time, the only available car is another car. Assuming that the average speed of the car is 40km / h and the speed of the passenger walking is 4km / h, there are three schemes (1) The car first takes four people to the railway station, the other three people wait in place, and then take the car back to the railway station (2) While the car takes four people to the railway station, the other three people walk first and then take the car back to the station (3) The car first takes four people to an underground car and returns. These four people walk to the station, while the other three people walk first and then take the car back to the station, and two groups of people arrive at the railway station at the same time Through calculation to determine whether these three schemes are feasible, if feasible, which scheme takes time?

Scheme 3 is the most reasonable, but the calculation is troublesome