A man goes to Chennai from Hyderabad at a speed of 24km/hr and returns to Hyderabad at speed of 40km/hr, through same route. What is his average speed (in km/hr) of the entire journey?

Correct option is D

​Given:
​Speed while going to Chennai = 24 km/h
​Speed while returning to Hyderabad = 40 km/h
​Formula Used:
​​$$\text{Average Speed} = \frac{2 \times \text{Speed 1} \times \text{Speed 2}}{\text{Speed 1} + \text{Speed 2}}$$​​​
​where,
​Speed₁ is the speed while going to Chennai,
​Speed₂ is the speed while returning to Hyderabad.
​Solution:
​​$$\text{Average Speed} = \frac{2 \times 24 \times 40}{24+ 40} \\\ \\\text{Average Speed} = \frac{2 \times 960}{64} = \frac{1920}{64} = 30 \, \text{km/h}$$​​​
​Thus, the average speed of the entire journey is 30 km/h.​