उत्तर : 1. "1 : 3"
व्याख्या :

Answer: A) 1 : 3 Explanation: Let the speed of the boat in still water is 'w' Speed of the current is 'c' Let the distance between two places is 'd' According to the question, motorboat takes half time to cover a certain distance downstream than upstream. dw+c = 12dw-c => 2w - 2c = w + c => w = 3c => c : w = 1 : 3   Hence, the ratio between rate of current(c) and rate of boat in still water(w) = 1 : 3