The different between downstream speed and upstream speed is 3 km/h and the total time taken during upstream and downstream is 3 hours. What is the downstream speed, if the downstream and upstream distances are 3 km each?

• Let Say Speed of Stream = x km/hr
  
  and speed of Rowing = y km/hr
  
  upstream spedd = y - x m/he
  
  Down stream speed = y + x km/Hr
  
  Difference between downstream & upstram speed = 3 km/hr
  
  y + x - (y -x) = 3
  
  => 2x = 3
  
  x = 3/2 km/Hr
  
  Speed of stream = 3/2 Km/hr
  
  Downstream speed = y +3/2 km/Hr
  
  Upstream speed = y - 3/2 km/hr
  
  Total Time taken = 3/(y +3/2)  + 3/(y-3/2)  = 3
  
  2/(2y +3)  + 2/(2y -3)  = 1
  
  => 4y - 6 + 4y + 6 = 4y² - 9
  
  => 4y² - 8y - 9 = 0
  
  => y = (8 + √64 + 144)/8
  
  => y = (8 + √208)/8
  
  => y = (8 + 14.42)/8
  
  => y = 22.42/8
  
  => y = 2.8 km/hr
  
  Downstream speed = y +3/2 km/Hr
  
  = 2.8 + 1.5
  
  = 4.3 km/Hr
• 5 years agoHelpfull: Yes(0) No(0)