A man row 12.8 km downstream in 32 min. River speed is 1/8th of downstream spd. If he goes A to B upstream and return to point A in 3.5 hour. Find the distance? ???

• speed of river = y kmph
  speed of boat = x kmph
  downspeed = x+y
  given , y= (x+y)/8
  so x = 7y..... (i)
  speed = dist / time
  x+y = 12.8*60/32 = 24... (ii)
  on solving (i) and (ii)
  y=3, x=21
  total time from A to B and back to A = 4 hours
  let d be distance between A and B
  3.5 = t1+t2
  3.5 = d/(x+y) + d/(x-y)
  3.5 = d/24 + d/18
  d = 36 Km (Answer)
• 9 years agoHelpfull: Yes(1) No(0)