Miscellaneous Question 84
- A boat can row $20 $ $km$ downstream in 24 minutes. The ratio of the speed of the boat in still water to the speed of the stream is $4: 1$. How much time will the boat take to cover $15$ $ km$ upstream?
(1) 25 minutes
(2) 30 minutes
(3) 33 minutes
(4) 28 minutes
(5) 23 minutes
IBPS Bank PO/MT CWE (Main Exam) 30.11.2019
Show Answer
Correct Answer: 84. (2)
Solution: 84. (2) Downstream speed $=\frac{\text { Distance }}{\text { Time }}$
$=\left(\frac{20}{24}\right) \times 60 $ $\mathrm{kmph}$
$=50$ $ \mathrm{km} / \mathrm{hr}$
Speed in still water : Speed of current $=4: 1=4 x: x$
$\Rightarrow$ Downstream speed $=4 x+x=5 x$
$\Rightarrow 5 x=50 \Rightarrow x=10$
$\therefore$ Upstream speed $=4 x-x=3 x$
$=3 \times 10=30$ $ \mathrm{kmph}$.
$\therefore$ Time taken $=\left(\frac{15}{30}\right) \times 60$ minutes
$=30$ minutes
BETA
