A motorist travel to a place 150 km away at an average speed of 70 km/hr and returns at 30 km/hr.His average speed for the whole journey in km/hr is	Select:
A) 36 km/hr
B) 37 km/hr
C) 40 km/hr
D) 42 km/hr
E) None of these
Explanation:   Average speed will be   2xy/x+y km/hr   = {2(70)(30)}/{70+30} km/hr   = 42 km/hr   Answer: Option 42 km/hr
<result>D</result>
A motorist travel to a place 150 km away at an average speed of 70 km/hr and returns at 30 km/hr.His average speed for the whole journey in km/hr is