There are two bridges running parallel over river Kauvery, and they are 1 KM apart. A man started rowing the boat upstream under first bridge, his hat fell into river while he was exactly under second bridge. He realized that after 15 mts, and started rowing in opposite direction, he eventually caught his hat under First Bridge. What is the speed of river Kauvery?

• Let the upstream velocity=xkm/h
  so he goes first 1 km then 15 min with this velocity
  so total goes=x*15/60+1 km=x+4/4 km
  and now he in downstream cover this distance in 15 min
  so his downstream velocity=x+4/4*15=x+4/60
  now speed of river=1/2[downstream speed-upstream speed]
  =1/2[x+4/60-x/60]km/min
  =2km/h
  
• 12 years agoHelpfull: Yes(7) No(0)
• According to the given condition extra distance covered after second bridge upstream = (v-u)/4
  here v and u are velocities of man in still water and that of river
  for downstream motion total time taken by man
  [1+{(v-u)/4}]/(v+u) = (4+v-u)/4(v+u)
  so for river or hat
  (4+v-u)/4(v+u) + 1/4 = 1/u
  or (4+v-u)/(v+u) + 1 = 4/u
  or (4+v-u+v+u)/(v+u) = 4/u
  or (4+2v)u = 4(v+u)
  or 4u+2uv = 4v + 4u
  or 2uv = 4v
  or u = 2
  
  
• 12 years agoHelpfull: Yes(2) No(3)