In a fixed time, a man swims double the distance along the current that he swims against the current. If the speed of the current is 3 km/hr, the speed of the man in still water is
Solution
Correct Answer: Option B
Let the distance covered by man against the current = d
So, the distance covered by man along the current = 2d
And let the speed of the man in still water = x
Given, speed of the current is = 3 km/hr
Time taken by man along the current = \(\frac{{2{\rm{d}}}}{{{\rm{\;x}} + 3}}\)
Time taken by man against the current = \(\frac{d}{{\;x - 3\;}}\)
∵ given that time is fixed
\(\therefore \frac{{2d}}{{\;x + 3}} = \frac{d}{{\;x - 3\;}}\)
⇒ 2x -6 = x + 3
⇒ x = 9
Hence, the speed of man in still water = 9kmph
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