A boat can row 30 km upstream and 44 km downstream in 10 hours. Also it can row 40 km upstream and 55 km downstream in 13 hours. What is the speed of the boat in still water? (a) 5 km/hour (b) 7 km/hour (c) 8 km/hour (d) 10 km/hour

• let in upstream x-y where x speed of boat in still water & y is speed of stream
  downstream x+y
  x-y=30/10-t1
  x+y=44/t1------------(1)
  
  x-y=40/13-t2
  x+y=55/t2---------(2)
  
  by equating eqn 1 and 2
  44/t1=55/t2
  t1=(4/5)t2
  now
  30/10-t1=40/13-t2
  by putting the value of t1
  t2=5
  from eqn 2
  x+y=11 & x-y=5
  x=8km/hr
  
• 9 years agoHelpfull: Yes(1) No(0)
• speed of boat in downstream=44/10=4.4 km/hr
  speed of boat in upstream=30/10=3 km/hr
  let speed of boat in still water be x km/hr
  let speed of river be=y km/hr
  x+y=4.4
  x-y=3
  ans . on solving x=5 km/hr
  
• 9 years agoHelpfull: Yes(0) No(3)