Subject: General Aptitude · Chapter: Boats and Streams · Exam: 2007 · Marks: · Difficulty:
A man can row 6 km/hr in still water. It takes him twice as long to row up as to row down the river. Find the rate of stream.
Answer
Answer (as printed):
Explanation
Let man's rate upstream be $x$ km/hr. Then, his rate downstream $=2x$ km/hr. ∴ Rate in still water $=\frac{1}{2}(x+2x)$ km/hr $=\frac{3x}{2}$ km/hr. So, $\frac{3x}{2}=6$ or $x=4$. ∴ Rate upstream $=4$ km/hr, Rate downstream $=8$ km/hr. Hence, rate of stream $=\frac{1}{2}(8-4)$ km/hr $=2$ km/hr.
Explanation as extracted from the printed page; notation may be imperfect.