A boat takes one fourth time in moving a certain distance in downstream than in upstream. The speed of the boat in still water is how much percentage more than the speed of current?

66.66%

If distance is constant, then ratio of speed = \(\frac{1}{ratio\;of\;time}\)

        Downstream    :     Upstream

Time           1            :          4

Speed        4            :          1

              Boat           :       Current

Speed   \(\frac{4+1}{2}\)          :           \(\frac{4-1}{2}\)

                5              :            3

Difference of speed = 2R

Speed of boat is = \(\frac{2}{3}\) × 100 = 66.66% more than the current.