A man walks from one place to another at a speed of 5 km/h and returns to the starting place of a speed of 1 km/h. His average speed for the whole journey is.
Correct Answer: Option D
Let the distance of one way be y km.
As he went and returned back,
Total distance = 2y
Time = Distance/speed
Time taken to cover y distance at speed of 5 km/hr = y/5
Time taken to cover distance y at speed of 1 km/hr = y/1
Total time taken for the whole journey = \(\frac{y}{5} + \frac{y}{1}\)
∴ Average speed = total distance/total time = \(\frac{{2y}}{{\frac{y}{5} + \frac{y}{1}}} = \frac{2}{{\frac{1}{5} + \frac{1}{1}}}\)
⇒Average speed = 1.66 km/hour
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