A boat takes twice time to go in upstream then the time taken by it to cover a certain distance in downstream. If speed of current is 3 km/hr then find the speed of boat in still water.

09 km/hr

                 Upstream(U.S.) : Downstream (D.S.)

Time :                      2        :          1

Speed :                   1        :          2

Therefore,

                       Current      :       Boat in still water

Speed :          (D.S.- U.S.)  :          (D.S. + U.S.)

                              1         :                  3

1R = 3km/hr (given)

3R = 3 × 3 = 9km/hr