A cow was standing on a bridge, 5 m away from middle of the bridge. A train was coming towards the bridge from the end nearest to the cow. seeing this the cow ran towards the train and managed to escape when the train was 2 m away from the bridge. If it had run in the opposite direction it would have been hit by the train 2m before the end of the bridge. What is the length of bridge in meters assuming speed of train is 4 times that of the cow.

• Let the total length of the bridge be '2x'.
  Now, the cow on seeing the train travels a distance of (x-5)m
  Let the distance traveled by the train in the same time be 'y'
  Since the time taken by the train and cow to travel a distance of (x-5)m and (y)m respectively is the same,
  s1/y = s2/(x-5)---(1)
  Given that s1 = 4s2---(2)
  hence, solving 1 and 2 will yield 4x-y=20---(3)
  
  Considering the second condition,
  s1/((y+2)+(2x-2)) = s2/(x+5-2)
  i.e. s1/(2x+y) = s2/(x+3)---(4)
  
  solving 2 and 4 we get
  2x-y= -12 ----(5)
  Now, solving 5 and 3 we get x=16
  Hence 2x = 32m is the answer..
  
• 10 years agoHelpfull: Yes(26) No(1)
• length of the bridge will be 32 m.
• 11 years agoHelpfull: Yes(8) No(3)
• let the length of the bridge is 2x
  the initial position of cow is 5m left to the middle of the bridge
  position of train is y mtrs left to the bridge,
  when cow moves to the left..... distances traveled by cow, train before crossing are (x-5+2), (y-2) respectively.
  let s1,s2 be the speeds of cow,train respectively. given s2=4s1.
  as w.k.t distance, speed are directly proportional, (x-3)/(y-2)=s1/4s1
  which gives 4x-y=10--------------------------(1)
  If cow moves to the right,distances are (x+3),(y+2x-2) respectively.
  similarly they gives 2x-y=-14-----------------(2)
  
  
  from solving 1 & 2, x= 12, y= 38
  so length = 2x = 24m
• 11 years agoHelpfull: Yes(4) No(11)
• 9.2m....equate distanc covered
  
• 11 years agoHelpfull: Yes(0) No(3)
• A P O COW B TRAIN
  |__|_______________|_______|_____________|....|X-3=(1/4)(6X-20)=>2x=8m
• 11 years agoHelpfull: Yes(0) No(3)
• i got 40m as length of the bridge.
• 10 years agoHelpfull: Yes(0) No(2)
• i think 11m is the answer.
• 8 years agoHelpfull: Yes(0) No(2)
• the answer would be 6 m and the equation would be
  4x-20=y
  2x-14=y
  solving both u will get x=3 y=-8 , therefore, length of bridge id 2x=6m
• 7 years agoHelpfull: Yes(0) No(0)