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60 km/h There, 40 km/h Back: What's the Real Average Speed?
A car travels a distance at 60 km/h and returns the same distance at 40 km/h. What is its overall average speed?
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What is the answer to the 60 there, 40 back average speed riddle?
The average speed is 48 km/h. Because the distance each way is equal, you must use the harmonic mean: 2 / (1/60 + 1/40) = 48 km/h.
Why isn't the average speed just 50 km/h?
50 is the average of the two speeds, but the car spends more time at the slower 40 km/h, so it weighs the result down. The true average over equal distances is 48 km/h.
How do you calculate average speed for a round trip?
For equal distances, average speed = total distance / total time. With 60 km/h out and 40 km/h back, that works out to the harmonic mean, 48 km/h, not the simple 50 km/h.