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BITSAT Question A boat takes time t to go downstream from point A to point B and time 2t to go upstream from point B to point A.

If the speed of the stream is v and the speed of the boat with respect to the stream is u, then which of the following gives the correct relationship between u and v

  1. u=v
  2. u=3v
  3. v=2u
  4. v=3u
Answers (1)
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Velocity of boat w.r.t stream is u 
Time taken by boat to go downstream, t = d/ (u+v)  ......(1)
Time taken by boat to go upstream, 2t = d/ (u-v)  .........(2)
From equation (1) and (2)
2*d/ (u+v) = d/ (u-v)
-> 2*(u-v) = (u+v)
-> u =3v 
Option (2) is correct

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