Question 49

A man rows to a place 48 km distant and back in 14 hours. He finds that he can row 4 km with the stream in the same time as 3 km against the stream. the rate of the stream is

Solution

Let speed of man = $$x$$ km/hr and speed of stream = $$y$$ km/hr

=> Downstream speed = $$(x+y)$$ km/hr and upstream speed = $$(x-y)$$ km/hr

According to ques, => $$\frac{4}{x+y}=\frac{3}{x-y}$$

=> $$4x-4y=3x+3y$$

=> $$x=7y$$ --------------(i)

Also, $$\frac{48}{x+y}+\frac{48}{x-y}=14$$

=> $$\frac{48}{8y}+\frac{48}{6y}=14$$

=> $$6+8=14y$$

=> $$y=1$$

$$\therefore$$ Speed of stream = 1 km/hr

=> Ans - (A)

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