Question
The speed of a boat in still water is 16/ 3 km/ h. It
was found that the boat takes thrice as much time to row up as it does to row down the same distance in the river stream. Find the speed of the river stream. (in m/sec)Solution
Let the speed of boat in still water =B and speed of stream =S then B=16/3 km/h Let the time taken in downstream =x Then time in upstream =3x Speed of boat in Downstream =B+S Speed of boat in Upstream=B-S Now ATQ-. (B-S)3x =x(B+S) (B-S)/(B+S) =x/3x (B-S) =x         … (1) (B+S) =3x      … (2) So, Solving after (1) +(2) B=2x, S=x Now- 2x = 16/3 x= 16/6=8/3 x =S = 8/3 ×5/18 Speed of stream = (20/27) m/s
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