Miscellaneous Question 60
- The difference between time taken by boat-A to cover $80 $ $km$ upstream and that taken to cover 80 $km$ downstream is 1 hour. If the respective ratio between its upstream and downstream speeds is $4: 5$, what distance will boat-A cover downstream in 2 hours? (in $km$ )
(1) 48
(2) 32
(3) 40
(4) 44
(5) 36
(Canara Bank PO Exam, 23.12.2018)
Show Answer
Correct Answer: 60. (3)
Solution: 60. (3) Rate downstream $=5 x $ $\mathrm{kmph}$
Rate upstream $=4 x $ $\mathrm{kmph}$
According to the question,
$\frac{80}{4 x}-\frac{80}{5 x}=1$
$\Rightarrow 80\left(\frac{5-4}{20 x}\right)=1$
$\Rightarrow 20 x=80$
$\Rightarrow x=\frac{80}{20}=4$
$\therefore$ Rate downstream of boat $=5 \times 4=20 $ $\mathrm{kmph}$
$\therefore$ Required distance $=20 \times 2=40 $ $\mathrm{km}$
BETA
