A person travels from A to B at an average speed of 60 km/hr and B to C at 50 km/hr and C to D at 40 km/hr. The distance from A to B, B to C and C to Dare equal. What is the average speed of the whole journey?

 a) 37.68 km/hr
 b) 48.65 km/hr
 c) 45.68 km/hr
 d) 50.00 km/hr

TNPSC Jailor-2016

48.65 km/hr. Solution Average speed is Harmonic mean of speeds in this case.