Question

A man can row a boat at 8 kmph in still water. If the speed of the river is 2 kmph , it takes 48 minutes to row to a place and come back. How far is the place from the starting point?

Answer 1

Speed of boat=8 km/hr
Speed of river=2 km/hr
Let the distance be d
Speed in upstream=(8-2)km/hr
                              =6 km/hr
Time=D/S
        =d/6 hrs
Speed in downstream=(8+2)km/hr
                              =10 km/hr
Time=D/S
        =d/10 hrs
Total time taken=48 mins
                         =48/60 hrs.
A.T.P
d/6+d/10=48/60
8d/30=48/60
d=48*30/60*8
d=3 km