A good train and a passenger train are running on the parallel tracks in the same direction.the driver of the goods train observe that the passanger train coming from behind, overtakes and crosses his train completely in 1 min whereas a passanger on the passanger train marks that he crosses the goods train in 2/3 minutes. the ratio of their length is?

4:1
3:1
1:2
none of these

• 1 : 2
  
  Let the length of goods train=x and g passenger train=y and
  Speed of goods train=g and passenger train=p , then their relative speed=p-g
  Time taken to cross goods train by passenger train=(x+y)/(p-g) =1 ----(i) and
  Time taken to cross goods train as seen by passenger in the passenger train= x/(p-g)=2/3 ----(ii)
  From (i) & (ii), x+y =3x/2 or 2y=x
  Hence ratio of lengths of goods train to passenger train=y/x =1/2 =1 : 2
  
• 8 years agoHelpfull: Yes(2) No(1)
• Both travelling in same direction then their relative speed is ( S1 -S2 )
  S1-S2 = D1/60 ( 1min equal to 60 sec)
  S1-S2 = D2/40 ( 2/3 min means 40 sec)
  By comparison
  D1/60=D2/40
  D1/D2 = 3:2 thats a right answer...
• 6 years agoHelpfull: Yes(0) No(0)