The question is :-A boat on a river travels downstream between two points 20 km apart in one hour.The return trip against the current taken two and half hours.What is the speed of the boat?
(A)8 km/hr (B)10 km/hr (C)14 km/hr (D)16km/hr
In water, the direction along the stream is called downstream. And, the direction against the stream is called upstream.
If the speed of a boat in still water is u km/hr and the speed of the stream is vkm/hr, then:
Speed downstream = (u + v) km/hr.
Speed upstream = (u - v) km/hr.
If the speed downstream is a km/hr and the speed upstream is b km/hr, then:
Speed in still water = 1 (a + b) km/hr. 2 Rate of stream = 1 (a - b) km/hr. 2
Rate upstream ==8
Speed in still water =(20+8) kmph = 14 km/hr