A man goes to Ahmedabad from Kolkata at a speed of 4km/hr and returns to Kolkata at speed of 12km/hr, through same route. What is his average speed (in km/hr) of the entire journey?

Correct option is B

Given:

Speed from Kolkata to Ahmedabad = 4 km/h

Speed from Ahmedabad to Kolkata = 12 km/h

Formula Used:

Average Speed = $$\frac{2 \times S_1 \times S_2}{S_1 + S_2}$$​​

Solution: 

Here: S₁ = 4 km/h and S₂ = 12 km/h

Average Speed = $$\frac{2 \times 4 \times 12}{4 + 12}$$​​

= $$\frac{96}{16}$$​​

= 6 km/h