A person travelled from his house to office at 30km/hr and office to house at 20km/hr. Then find the average speed?  Choose the most appropriate option
A) 15km/hr  B) 20km/hr  C) 32km/hr  D) 24km/hr  E) 25km/hr
Average speed = (2*30*20)/(30+20)= 
<gadget id="calculator">(2*30*20)/(30+20)</gadget>
<output>24</output>
24km/hr   Answer is 24km/hr
<result>D</result>
A person travelled from his house to office at 30km/hr and office to house at 20km/hr. Then find the average speed?