Question: A train travels from City A to City B at a speed of 60 km/h and returns at a speed of 90 km/h. What is the average speed of the train for the entire journey?
Options:
Correct Answer: 72 km/h
Solution:
Average speed = 2xy / (x + y) = 2 * 60 * 90 / (60 + 90) = 72 km/h.