A motorist travels to a place 150 km away at an average speed of 50 km/hr and returns at 30 km/hr. His average speed for the whole journey in km/hr is?
Choose the correct answer:
A) 37.9  B) 37.53  C) 37.5  D) 37.1  E) 37.4

Rationale: explanation : average speed = ( 2 xy ) / ( x + y ) km / hr = ( 2 * 50 * 30 ) / ( 50 + 30 ) km / hr . 37.5 km / hr . answer : c
Answer: C