A motorist travel to a place 150 km away at an average speed of 45 km/hr and returns at 30 km/hr.His average speed for the whole journey in km/hr is  Choose the correct choice from the following options:
A) 36 km/hr  B) 37.5 km/hr  C) 35.5 km/hr  D) 34.5 km/hr  E) None of these
Explanation:   36 km/hrverage speed will be   2xy/x+y km/hr   = {2(45)(30)}/{45+30} km/hr   = 36 km/hr   36 km/hrnswer: Option 36 km/hr
<result>A</result>
A motorist travel to a place 150 km away at an average speed of 45 km/hr and returns at 30 km/hr.His average speed for the whole journey in km/hr is