Miscellaneous Question 50
- The boat’s speed in still water is 9.6 times the stream’s speed. If the boat covers $43 $ $km$ upstream in $2 $ hrs, how much time will it take to cover $159 $ $km$ downstream?
(1) 5 hours
(2) 7 hours
(3) 7 hours 30 minutes
(4) 6 hours 30 minutes
(5) 6 hours
(IBPS RRBs Officer CWE (Prelim Exam) 11.08.2018)
Show Answer
Correct Answer: 50. (5)
Solution: 50. (5) Speed of current $=x $ $\mathrm{kmph}$
$\therefore$ Speed of boat in still water $=$ $9.6 x $ $\mathrm{kmph}$.
Rate upstream of boat
$=\frac{43}{2}=21.5$ $ \mathrm{kmph}$.
$\Rightarrow 9.6 x-x=21.5$
$\Rightarrow 8.6 x=21.5$
$\Rightarrow x=\frac{21.5}{8.6}=2.5$ $ \mathrm{kmph}$.
$\Rightarrow$ Rate downstream $=10.6 x$
$=10.6 \times 2.5=26.5 $ $\mathrm{kmph}$.
$\therefore$ Time taken in covering 159 km downstream
$=\frac{159}{26.5}=6$ hours
BETA
