Boat and Stream is one of the most frequently asked topics in the law entrance test. Before learning the concepts of the test one should be aware of the words used in the questions. Download CLAT Question Papers to practice Boat and Stream questions.
Important Boat and Stream Terminologies & Formulae
Over the river
- When the boat is moving against the current of the river (i.e. vice versa), then the relative speed of the boat is the difference between the speed of the boat and the flow. It is known for its speed up the river.
- Remember that HIGH as a hill climb means against the direction of force (speed) of a river.
- If the speed of a boat or swim is x km / h and the speed of the stream is y km / h then,
- Speed of boat upstream = (x - y) km / h
Down the river
- When a boat travels along a river (i.e. on the same side), then the relative speed of the ship is the sum of the speed of the boat and the stream. It is known for the speed at the bottom of the river.
- Remember it is DOWN as the descent means going to the power (speed) of the river.
- If the speed of a boat or swim is x km / h and the speed of the stream is y km / h then,
- Boat speed downstream = (x + y) km / h
Check CLAT UG Syllabus 2024 and Download PDF
Key Points about Boat and Stream
When the speed of a ship is given it means that the speed at the water is motionless unless otherwise stated.
Some Basic Formulas
The speed of the boat in stagnant water is such
= ½ (River Speed + River Speed)
The speed of the broadcast is
= ½ (River speed - uphill speed)
CLAT Boat and Stream Questions
1. Azhar can row 9.333 kmph in still waters and finds that it takes him thrice as much time to row up than as to row down the same distance in the river. The speed of the current of the river is
- 3.333 km/hr
- 3.111 km/hr
- 4.666 km/hr
- 4.5 km/hr
- Let the speed of the current of the river be S.
- Speed upstream = 9.333 – S
- Speed downstream = 9.333 + S
- Given that, 9.333 + S = 3(9.333 - S)
- => 9.333 + S = 28 – 3S
- => 4S = 18.667
- => S = 4.666 km/hr
2. A streamer goes downstream from one part to another in 4 hours. It covers the same distance in upstream in 5 hours. If the speed of the stream is 2 km/h, the distance between the two ports is ___.
- 80 km
- 81 km
- 70 km
- 71 km
- Let the distance between two ports be D.
- Speed of boat in still water be ‘s’
- Speed of the stream = 2 km/h
- Speed of boat in upstream = (s – 2) km/h
- Speed of boat in downstream = (s + 2) km/h
- According to the question,
- D/ (s + 2) = 4 hour ……(1)
- D/ (s – 2) = 5 hour …….(2)
- After solving Eq. (1) & (2)
- Speed of boat (s) = 18 km/h …….. (3)
- Putting eq. (3) in eq. (1), we get D = 80 km
3. A man can row 14 km/h in still water. In the stream flowing with the speed of 10 km/h he takes 4 hours to move with the stream and come back. Find the distance he rowed the boat.
- 11.71 km
- 13.71 km
- 14.71 km
- 12.71 km
- Let the distance be D.
- Speed of boat in still water = 14 km/h
- Speed of the stream = 10 km/h
- Speed of boat in upstream = (14 – 10) = 4 km/h
- Speed of boat in downstream = (14 + 10) = 24 km/h
- According to the question,
- D/ (24) + D/ (4) = 4 hour
- 7D/ (24) = 4 hour
- D = 13.71 km
4. X, Y and Z are three points on the same bank of a river such that Y is the midpoint of XZ. A boat can go from point X to Y and return back in 12 hours. Also, it goes from point X to Z in 16 hours. How long would it take to go from point Z to X?
- 4 hours
- 6 hours
- 8 hours
- 16 hours
- Distance from point X to Z = 2 × Distance from X to Y
- If the boat takes 12 hrs to go from X to Y and return back then it must take 2 × 12 = 24 hours to go from point X to Z and return back.
- Also given that the time is taken to go from point X to Z = 16 hours
- So, time taken to go from point Z to X = 24 – 16 = 8 hours
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