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Question

A boatman can row to a place (Y) at a distance of 24 km from the starting point (X) and back in 14 hours. If he can row 4 km with the stream in the same time as he can row 3 km against it, what is the speed of the stream?

This question was previously asked in
CDS 2 2026 Maths Question Paper (13-Sep-2026)
The correct answer is

0.5 km/hr

Let the boat's speed in still water be \(b\) and the stream's speed be \(s\). From \(\frac{4}{b+s}=\frac{3}{b-s}\), we get \(4(b-s)=3(b+s) \Rightarrow b=7s\). Using \(\frac{24}{b+s}+\frac{24}{b-s}=14\) with \(b+s=8s\) and \(b-s=6s\): \(\frac{3}{s}+\frac{4}{s}=14 \Rightarrow \frac{7}{s}=14 \Rightarrow s=0.5\) km/hr.

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Similar Questions

  1. A motor boat has speed 30 km/hr in still water. It goes 60 km down stream and comes back in 9/2 hours. What is the speed of the stream?

  2. A man rows down a river 18 km in 4 hours with the stream and returns in 10 hours. Consider the following statements:

    (1) The speed of the man against the stream is 1.8 km/h

    (2) The speed of the man in still water is 3.15 km/h

    (3) The speed of the stream is 1.35 km/h

    Which of the above statements are correct?

  3. A man can row at a speed of x km/h in still water. If in a stream which is flowing at a speed of y km/h it takes him z hours to row to a place and back, then what is the distance between the two places?

  4. A person can row downstream 20 km in 2 hours and upstream 4 km in 2 hours. What is the speed of the current?

  5. The speed of a boat in still water is 15 km/hr. If it can travel 42 km downstream and 28 km upstream in the same time, then what is the speed of the stream ?  


Important Questions from Boat and River

  1. A boat sails 15 km of a river towards upstream in 5 hours. How long (in hours) will it take to cover the same distance downstream, if the speed of river is one-fourth the speed of the boat in still water?

  2. The speed of boat upstream is 5 kmph. Its speed in still water is 10 kmph. How many minutes will it take to row 25 km downstream?

  3. Sudha can travel a certain distance downstream in 6 hours by boat and return to the starting point in 9 hours. If the stream flows at a speed of 3 km/h, how long (in hours) will it take to cover a distance of 67.5 km in still water?

  4. The downstream speed of a boat is 20 km/hr and the speed of stream is 4 km/hr. What will be the total time taken by the boat to cover 160 km downstream and 96 km upstream?

  5. The ratio of the speeds of a boat in still water and the speed of the river is 3 ∶ 1. The boat takes 45 minutes for a round trip journey. Find the distance of the whole trip if the speed of the stream is 4 km/hr.

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