Two buses leave school moving on opposite directions. After 15 minutes, they are both 10 miles away from the school. Which statements correctly describe the motion of the buses?

The correct answer is B. The average speed of the buses is equal.

Explanation:

Both buses have traveled the same distance after fifteen minutes, but this does not mean that their speed has been constant because they have had to face different traffic, traffic lights and roads. Even one of them may have had to stop longer than the other, but then it has compensated for that time stopped with greater speed, if traffic conditions allowed. Finally, both have traveled ten miles in fifteen minutes, which means that their average speed is the same.