Subject: General Aptitude · Chapter: Boats and Streams · Exam: · Marks: · Difficulty:
A boatman goes 2 km against the current of the stream in 1 hour and goes 1 km along the current in 10 minutes. How long will it take to go 5 km in stationary water?
(a)40 minutes
(b)1 hour
(c)1 hr 15 min
(d)1 hr 30 min
Answer
Answer (as printed):
Explanation
Rate downstream $=\left(\frac{1}{10} \times 60\right) \mathrm{km} / \mathrm{hr}=6 \mathrm{km} / \mathrm{hr}$; Rate upstream $=2 \mathrm{km} / \mathrm{hr}$. Speed in still water $=\frac{1}{2}(6+2) \mathrm{km} / \mathrm{hr}=4 \mathrm{km} / \mathrm{hr}$. ∴ Required time $=\left(\frac{5}{4}\right) \mathrm{hrs}=1 \frac{1}{4} \mathrm{hrs}=1 \mathrm{hr} 15 \mathrm{min}$.