A man jumps into a river from a overbridge ,at the same time a hat drops in the river which flows with the stream of the water. That man travels 10 minute upstream and returns back where he was asked to catch the hat. He catches hat at a distance of 1000 yard down at a second bridge . Find the speed of the river.

• Suppose x is the distance travelled by the man in 10 min upstream.
  Then
  x/(v-u) = 10 where v is man's speed and u is river speed)
  
  total time taken to swim by the man upstream and down stream is equal to the time taken by the hat to travel 1000 yards with the speed of river
  
  1000/u = 10 + (x+1000)/(u+v)
  now substitute x = 10(v-u) and simplify
  we will get
  100v = 2uv
  means
  2u = 100 and u = 50 yards per minute
• 14 years agoHelpfull: Yes(2) No(0)
• cosidering second bridge as same bridge from which man & hat fall
  time taken by man to travel in upstream is 10 min
  man first travel upstream for 10 min and then with the flow of water let dist travel by man upstream is a ,vel of man=x,vel of river=y
  a=10(x-y)and 10+a/(x+y)+1000/(x+y)=1000/y.
  we get y=50.
• 14 years agoHelpfull: Yes(0) No(0)