Boats and Streams Questions and Answers updated daily – Aptitude



15 Boats and Streams Questions and answers section with explanation for various online exam preparation, various interviews, Aptitude Boats and Streams online test. Boats and Streams Questions with detailed description, explanation will help you to master the topic.

Boats and Streams Questions

1. If a boat goes 7 km upstream in 42 minutes and the speed of the stream is 3 kmph, then the speed of the boat in still water is



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Correct Ans:13 kmph
Explanation:
Rate upstream = (7/42)*60 kmh = 10 kmph. Speed of stream = 3 kmph.
Let speed in sttil water is x km/hr
Then, speed upstream = (x —3) km/hr.
x-3 = 10 or x = 13 kmph.


2. A boat takes 4 hours for travelling downstream from point A to point B aild coming back to point A upstream. If the velocity of the stream is 2 kmph and the speed of the boat in still water is 4 kmph, what is the distance between A and B?



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Correct Ans:6 km
Explanation:
Let the distance between A and B be x km.
Speed downstream = 6 kmph, speed upstream = 2 kmph.
(x/6) + (x/2) = 4 4x = 24 hence x = 6
Distance AB = 6 km.


3. If a man can swim downstream at 6 kmph and upstream at 2 kmph, his speed in still wateris



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Correct Ans:4 kmph
Explanation:
Speed in still water = (1/2) * (6 + 2) km/hr = 4 km/hr


4. A man rows 750 m in 675 seconds against the stream and returns in 7 and half minutes. His rowing speed in still water is:



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Correct Ans:5 kmph
Explanation:
Rate upstream = (750/675) = 10/9 m/sec
Rate downstream (750/450) m/sec = 5/3 m/sec.
Rate in still water = (1/2)*[(10/9) + (5/3)] m/sec. = 25/18 m/sec
= (25/18)*(18/5) kmPh = 5 kmph


5. A boat covers 24 km upstream and 36 km downstream in 6 hours while it covers 36 km upstream and 24 km downstream in 6 hours. The velocity of the current is



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Correct Ans:2 kmph
Explanation:


6. A man can row a boat at 10 kmph in still water. If the speed of the stream is 6 kmph, the time taken to row a distance of 80 km down thestream is 



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Correct Ans:5 hours
Explanation:
Speed downstream (10+6) km/hr 16 km/hr.
Time taken to cover 80 km downstream = (80/16) hrs = 5 hrs


7. A man rows 13 km upstream in 5 hours and also 28 km downstream in 5 hours. The velpciy of the stream is



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Correct Ans:1.5 kmph
Explanation:
speed upstream = (13/5) kmph
speed downstream (28/5) kmph
Velocity of stream = (1/2)[(28/5) - (13/5)] = 1.5 kmph


8. If anshul rows 15 km upstream and 21 km downstream taking 3 hours each time, th’en the speed of the stream is 



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Correct Ans:1 kmph
Explanation:
Rate upstream = (15/3) kmph
Rate downstream (21/3) kmph = 7 kmph.
Speed of stream (1/2)(7 - 5)kmph = 1 kmph.


9. The speed of a boat in still water in 15 km/hr and the rate of current is 3 km/hr. The distance travelled downstream in 12 minutes is:



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Correct Ans:3.6 km
Explanation:
Speed downstream = (15 + 3) kmph = 18 kmph.

Distance travelled = 18 x 12 / 60km = 3.6 km.



10. In one hour, a boat goes 11 km/hr along the stream and 5 km/hr against the stream. The speed of the boat in still water (in km/hr) is:



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Correct Ans:8 km/hr
Explanation:
Speed in still water =1(11 + 5) / 2 kmph = 8 kmph.
2



11. A man's speed with the current is 15 km/hr and the speed of the current is 2.5 km/hr. The man's speed against the current is:



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Correct Ans:10 km/hr
Explanation:
Man's rate in still water = (15 - 2.5) km/hr = 12.5 km/hr.

Man's rate against the current = (12.5 - 2.5) km/hr = 10 km/hr.


12. A man takes twice as long to row a distance against the stream as to row the same distance in favour of the stream. The ratio of the speed of the boat in still water and stream is



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Correct Ans:3:1
Explanation:
Let speed downstream = x kmph
Then Speed upstream = 2x kmph

So ratio will be,
(2x+x)/2 : (2x-x)/2
=> 3x/2 : x/2 => 3:1


13. A man rows 750 m in 675 seconds against the stream and returns in 7 and half minutes. His rowing speed in still water is



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Correct Ans:5 kmph
Explanation:
Rate upstream = (750/675) = 10/9 m/sec
Rate downstream (750/450) m/sec = 5/3 m/sec
Rate in still water = (1/2)*[(10/9) + (5/3)] m/sec.
= 25/18 m/sec
= (25/18)*(18/5) kmph
= 5 kmph


14. In one hour, a boat goes 11km along the stream and 5 km against it. Find the speed of the boat in still water



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Correct Ans:8
Explanation:
We know we can calculate it by 1/2(a+b)

=> 1/2(11+5) = 1/2(16) = 8 km/hr


15. A man can row upstream 10 kmph and downstream 20 kmph. Find the man rate in still water and rate of the stream.



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Correct Ans:15,5
Explanation:
Please remember,
If a is rate downstream and b is rate upstream
Rate in still water = 1/2(a+b)
Rate of current = 1/2(a-b)

=> Rate in still water = 1/2(20+10) = 15 kmph
=> Rate of current = 1/2(20-10) = 5 kmph



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