Find avrg speed if a man travels at speed of 18km/hr up and 24km/hr dawn at an altitude of 300m.  Choose the correct choice from the following choices:
A) 25.8	B) 26.8	C) 27.8	D) 20.5	E) 21.8
avg speed=2*x*y/(x+y)   =2*18*24/(18+24)=20.5   ANSWER:20.5
<result>D</result>
Find avrg speed if a man travels at speed of 18km/hr up and 24km/hr dawn at an altitude of 300m.