Question 86

Speed of a man in still water is $$(\frac{28}{3})$$ km/h. It takes him thrice as much time to row upstream as it takes to row downstream. What is the velocity of the stream?

Solution

Speed of a man in still water is (28/3) km/h

Let say speed of stream = S/3 km/hr

Speed of Man downstream = (28+S)/3 km/hr

Speed of Man upstream = (28 -S)/3 km/Hr

Time taken for a given distance = D

D/( (28 -S)/3) = 3 * D/((28+S)/3)

=> 28+S = 3 (28 - S)

=> 28 + S = 84 - 3S

=> 4S = 56

=> S = 14

S/3 = 14/3

B is correct choice.

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