Arithmatical - Boat’s and Streams

Important Facts and Formulae

Downstream/Upstream :

In water, the direction along the stream is called downstream.

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 v km/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 = 1⁄2 (a + b) km/hr.

Rate of stream = 1⁄2 (a - b) km/hr.