Subject: General Aptitude · Chapter: Boats and Streams · Exam: 2004 · Marks: · Difficulty:
A man can row at 5 kmph in still water. If the velocity of current is 1 kmph and it takes him 1 hour to row to a place and come back, how far is the place?
(a)2.4 km
(b)2.5 km
(c)3 km
(d)3.6 km
Answer
Answer (as printed): A
Explanation
Speed downstream $=(5+1) \mathrm{kmph}=6 \mathrm{kmph}$; Speed upstream $=(5-1) \mathrm{kmph}=4 \mathrm{kmph}$. Let the required distance be $x \mathrm{km}$. Then, $\frac{x}{6}+\frac{x}{4}=1 \Leftrightarrow 2 x+3 x=12$ $$\Leftrightarrow 5 x=12 \Leftrightarrow x=2.4 \mathrm{km} .$$