Miscellaneous Question 93
- The time taken by a boat to cover a certain distance upstream is $50 \%$ more than it takes to travel the same distance downstream. If the speed of the current is $3 $ $km / h$, what is the speed of the boat in still water?
(1) 10
(2) 12
(3) 13
(4) 15
(5) 16
(Indian Bank Specialist Officer SO Exam, 08.03.2020)
Show Answer
Correct Answer: 93. (4)
Solution: 93. (4) Speed of boat in still water $=$ $x$ kmph (let)
$\therefore$ Rate downstream
$=(x+3) $ $\mathrm{kmph}$
Rate upstream
$=(x-3) $ $\mathrm{kmph}$
Let the required distance be $y$ $\mathrm{km}$.
$ \begin{aligned} & \text { Time }=\frac{\text { Distance }}{\text { Speed }} \\ & \therefore \frac{y}{x-3}=\frac{y}{x+3} \times \frac{150}{100}=\frac{y}{x+3} \times \frac{3}{2} \\ & \quad \Rightarrow 2(x+3)=3(x-3) \end{aligned} $
$\Rightarrow 2 x+6=3 x-9$
$\Rightarrow 3 x-2 x=9+6$
$\Rightarrow x=15 $ $\mathrm{kmph}$
BETA
