Suresh drives his car to a place 150 km away at an average speed of 50 km/hr and returns at 30 km/hr. What is his average speed for the whole journey ?  Options:
A) 32.5 km/hr  B) 35 km/hr  C) 37.5 km/hr  D) 40 km/hr  E) 42 km/hr
Explanation:   If a car covers a certain distance at x kmph and an equal distance at y kmph. Then,   average speed of the whole journey = 2xy/x+y kmph.   Therefore, average speed   =2×50×30/50+30=2×50×30/80   =2×50×3/8=50×3/4   =25×3/2=75/2= 
<gadget id="calculator">75/2</gadget>
<output>75/2 = around 37.5</output>
37.5   Answer: Option 37.5 km/hr
<result>C</result>
Suresh drives his car to a place 150 km away at an average speed of 50 km/hr and returns at 30 km/hr. What is his average speed for the whole journey ?