Miscellaneous Question 35
- A dual-engine boat covered $95$ $ km$ downstream in 5 hours. Later, one of the engines developed a snag and the boat covered the same distance upstream in 19 hours. By what per cent did the boat’s speed in still water reduce? (The stream flowed at a constant speed of $4$ $ km / hr$ )
(1) 40
(2) 60
(3) 50
(4) $68 \frac{2}{3}$
(5) 25
(IBPS RRBs Officers CWE (Prelim Exam) 09.09.2017 IInd Sitting)
Show Answer
Correct Answer: 35. (1)
Solution: 35. (1) Rate downstream of dual-engine boat $=\frac{95}{5}=19 $ $\mathrm{kmph}$.
Its speed in still water $=19-4=15 $ $\mathrm{kmph}$.
Rate upstream of single engine boat $=\frac{95}{19}=5 $ $\mathrm{kmph}$.
Its speed in still water
$=5+4=9 $ $\mathrm{kmph}$.
Required per cent
$=\left(\frac{15-9}{15}\right) \times 100$
$=\frac{600}{15}=40 \%$
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