Question

Amol goes from Ahmedabad to Lucknow at the speed of 40 km/hr and returned at the speed of 60 km/hr. What is the average speed of Amol during the whole journey?​

Answer 1

Given:

Speed when he is going from Lucknow to Ahmedabad (v₁)= 40km/hr

Speed during the return journey (v₂) = 60 km/hr

To Find:

Average speed of Anmol during the whole journey

Solution:

Let the distance between Ahmedabad and Lucknow be x

Distance, time, and average speed are related by the formula:

$Average speed = \frac{ Total distance}{Total Time}$ .........(a)

For the complete journey, the total distance covered will be (x + x) = 2x

And formula to calculate time is,

$Time = \frac{Distance}{Speed}$..............(b)

⇒ t₁ = x /40 and t₂ = x /60

Putting the values in eq (a), we get

$Average speed = \frac{2x}{\frac{x}{40} + \frac{x}{60} }$

⇒ $\frac{2x}{\frac{3x + 2x}{120}}$

⇒ $\frac{2x}{5x}X120$

⇒ 48

Hence, the average speed of Amol during the whole journey is 48 km/hr