A train travels from City A to City B at an average speed of 60 miles per hour. On the return trip from City B to City A along the exact same track, it travels at an average speed of 40 miles per hour. What is the train's average speed for the entire round trip?
48 miles per hour
To find average speed over equal distances, use the harmonic mean: (2 * S1 * S2) / (S1 + S2). Calculation: (2 * 60 * 40) / (60 + 40) = 4800 / 100 = 48 mph.
About this riddle
Logic riddles give you a few facts and ask what must be true. List what you know, cross out what cannot be, and see what is left.
Difficulty: Medium. More like this: Logic riddles with answers or try Einstein's Logic Grid for a different kind of puzzle.
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