A scooterist moves from a place A to place B with a uniform speed of 30km/hr and returns from B to A with a uniform speed of 50km/hr. Find the average speed for the complete journey.

Let the distance between A and B be  x km.

We Know that Average Speed = Total Distance /Total time taken.

Now time taken in going from  A to  B = t1= x/30 

Time taken in returning from  B to A = t2 = x/50

Now total time taken in entire journey = t1+t2 = x/30 + x/50

Now Average Speed = Total Distance/Total Time taken.

=>  

Ans = 37.5 Km/hr