Calculate the speed of a boat in still water (in km/hr) if in one hour, the boat goes 15 km/hr downstream and 7 km/hr upstream.
Options:
(A) 12 kmph
(B) 13 kmph
(C) 14 kmph
(D) 15 kmph
(E) 11 kmph Stream of consciousness:
Speed in still water = (15 + 7)1/2 kmph = 11 kmph.
Thus, the answer is (E).