【18】A column of soldiers 600 meters long is marching at a speed of 2 meters per second. A soldier needs to run from the end of the column to the front, and then immediately return to the end. If he runs at a speed of 3 meters per second, the total distance he travels back and forth is ( ) meters.
【Key Point】Travel Problem: Train passing a person.
【Analysis】The soldier rushing from the end of the line to the front is a catch-up problem between a person and a line, catch-up time: $600 \div(3-2)=600$ (seconds); the soldier returning from the front to the end of the line is a meeting problem between a person and a line, meeting time: $600 \div(3+2)=120$ (seconds); therefore, he traveled back and forth for a total of $600+120=720$ seconds.

【Answer】720