A man covers a distance at 40 km/h and returns along the same road at 60 km/h. His average speed for the whole journey is:

Question

Arvind went from point A to B and Surubhi from B to A. They met somewhere between continuing their journey. Arvind took 6 hours and Surubhi took 24 hours to reach the respective destinations after meeting. If Aravind traveled 54 Kmph, what is the distance AB.

Answer 1

Step 1: For equal distances, average speed \(= \dfrac{2ab}{a+b}\) (harmonic mean).
Step 2: \(= \dfrac{2\times40\times60}{40+60} = \dfrac{4800}{100} = 48\) km/h.

Quick Tip: Equal-distance average speed is the harmonic mean, never the plain average.

A man covers a distance at 40 km/h and returns along the same road at 60 km/h. His average speed for the whole journey is:

The Correct Option is A

Solution and Explanation

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