Subject: General Aptitude · Chapter: Boats and Streams · Exam: · Marks: · Difficulty:
A boat running upstream takes 8 hours 48 minutes to cover a certain distance, while it takes 4 hours to cover the same distance running downstream. What is the ratio between the speed of the boat and speed of the water current respectively ?
(a)2 : 1
(b)3 : 2
(c)8 : 3
(d)Cannot be determined
(e)None of these
Answer
Answer (as printed): C
Explanation
Let the man' rate upstream be $x$ kmph and that downstream be $y \mathrm{kmph}$. Then, Distance covered upstream in 8 hrs 48 min. = Distance covered downstream in 4 hrs. $$\Rightarrow \quad\left(x \times 8 \frac{4}{5}\right)=(y \times 4) \Rightarrow \frac{44}{5} x=4 y \Rightarrow y=\frac{11}{5} x .$$ ∴ Required ratio $$=\left(\frac{y+x}{2}\right):\left(\frac{y-x}{2}\right)=\left(\frac{16 x}{5} \times \frac{1}{2}\right):\left(\frac{6 x}{5} \times \frac{1}{2}\right)=\frac{8}{5}: \frac{3}{5}=8: 3 .$$
Explanation as extracted from the printed page; notation may be imperfect.