Ravi and Ajay start simultaneously from the same place A and reach at place B, 60 km apart. Ravi's speed is 4 km/hr less than that of Ajay. Ajay, after reaching place B, returns and meets Ravi at a place 12 km away from B. Find the speed (in km/hr) of Ravi.

Concept Used:-

The time required to cover a distance by an object is equal to the ratio of distance to the speed of the object.

⇒ Time = Distance / Speed

Explanation:-

Suppose the speed of Ravi = x km/hr.
So, the speed of Ajay = (x + 4) km/hr.

According to the question, the distance travelled by Ajay, 

⇒ 60 + 12 = 72 km
Also, the distance travelled by Ravi, 
⇒ 60 − 12 = 48 km
Now, the point of meet the time taken by Ravi and Ajay will be same as they started at the same time. Thus,

⇒ Time taken by Ajay = Time taken by Ravi

\( \Rightarrow \dfrac{72}{x+4}=\dfrac{48}{x} \\ \Rightarrow 3 x=2 x+8 \\ \Rightarrow x=8 \mathrm{~km} / \mathrm{hr} \)

So, the speed of Ravi is 8 km/hr. 

Hence, the correct option is 3.