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A man rows to a place 48 km distant and come 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:
Answer & Solution
Correct Answer:
Option
A
Suppose he move 4 km downstream in x hours
Then,
Speed downstream = $$\frac{4}{x}$$ km/hr
Speed upstream = $$\frac{3}{x}$$ km/hr
$$\eqalign{ & \therefore \frac{{48}}{{\left( {4/x} \right)}} + \frac{{48}}{{\left( {3/x} \right)}} = 14\,or\,x = \frac{1}{2} \cr} $$
So, Speed downstream = 8 km/hr
Speed upstream = 6 km/hr
∴ Rate of the stream
= $$\frac{1}{2}$$(8 - 6) km/hr
= 1 km/hr
Then,
Speed downstream = $$\frac{4}{x}$$ km/hr
Speed upstream = $$\frac{3}{x}$$ km/hr
$$\eqalign{ & \therefore \frac{{48}}{{\left( {4/x} \right)}} + \frac{{48}}{{\left( {3/x} \right)}} = 14\,or\,x = \frac{1}{2} \cr} $$
So, Speed downstream = 8 km/hr
Speed upstream = 6 km/hr
∴ Rate of the stream
= $$\frac{1}{2}$$(8 - 6) km/hr
= 1 km/hr
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