Final answer:
The total distance covered by the train is the sum of the distances traveled in both directions, which is 6 km out plus 3 km back, making it a total of 9 km.
Step-by-step explanation:
The question asks to find the total distance covered by a train which first goes 6 km away from the starting point in a positive direction along a straight track, and then returns back for 3 km. To find the total distance covered, we simply add the distances of the two segments of the trip together.
- The train first travels 6 km away from the starting point.
- Then the train comes back 3 km towards the starting point.
- We add these two distances together to get the total distance: 6 km + 3 km = 9 km.
Therefore, the total distance covered by the train is 9 km, which corresponds to option C.