A person travels from Kolkata to Ahmedabad at a speed of 9km/hr and returns back to Kolkata by the same route at a speed of 18 km/hr. Find his average speed (in km/hr) during the entire journey. एक व्यक्ति 9km/hr की चाल से कोलकाता से अहमदाबाद जाता है तथा उसी मार्ग से 18 km/hr की चाल से कोलकाता वापस आता है। पूरी यात्रा के दौरान उसकी औसत चाल (km/hrमें) ज्ञात कीजिए।

A person travels from Kolkata to Ahmedabad at a speed of ... - Direction MCQ Solution

Solution:

For equal distances, average speed:
$ \frac{2ab}{a+b} $

Here $a = 9$, $b = 18$

$ \frac{2 \times 9 \times 18}{9 + 18} = \frac{324}{27} = 12 $

✅ Final Answer: 12 km/hr