A and B are two stations 300 km apart. Two trains T1 and T2 start from A and B respectively, towards each other at the same time. T1 reaches B nine hours and T2 reaches A four hours after they meet. Find the difference between the speeds of T1 and T2.
(a) 10 km/hr (b) 15 km/hr (c) 20 km/hr (d) 25 km/hr

• ans: option (a)
  Let the speed of train T1 is S1 and that of T2 is S2.
  w.k.t speed is inversely proportional to time
  (S1/S2) = sqrt of (4/9)
  (S1/S2) = 2/3-------(1)
  S1=2S2/3
  now, 9S1+4S2=300-----------(2),
  9(2s2/3)+4s2=300
  s2=30
  On solving these equation we get, S1=20 km/hr therefore S2-S1=10 km/hr
• 10 years agoHelpfull: Yes(19) No(1)
• ans: option (b)
  Let the speed of train T1 is S1 and that of T2 is S2.
  w.k.t speed is inversely proportional to time
  (S1/S2) = sqrt of (4/9)
  (S1/S2) = 2/3-------(1)
  now, 9S1+4S2=300-----------(2), On solving these equation we get, S1=30 km/hr and S2=45km/hr. therefore S2-S1=15 km/hr
• 10 years agoHelpfull: Yes(9) No(35)
• train T1 will take t hours from A to the meeting point and then it will take 9 hrs. train T2 will take t hrs from B to the meeting point and then it will take 4 hrs to reach to A. So if we take the ratio it will be t/4=9/t. so t=6. therefore distance 300 km and time taken by train T1 and T2 is 15(6+9) hrs and 10(4+6) hrs. so, speed of T1 is 20km/hr and speed of T2 is 30 km/hr. so, Speed diff is 10 km/hr(answer)
• 10 years agoHelpfull: Yes(8) No(0)
• i think the ans is 10km/hr.
• 10 years agoHelpfull: Yes(5) No(1)
• why they are taking square root of(4/9)? explain
• 9 years agoHelpfull: Yes(5) No(0)
• whenever two things crosses a point after meeting.........
  let two train A start from point R another B from S meet at P
  after P , A takes t1 time to reach S
  and B takes t2 time to reach P..........
  hence speed ratio of both the train is...........Va/Vb=sq. rt(t2/t1)
  remember it is very helfull..............
• 8 years agoHelpfull: Yes(3) No(0)
• @VIKASH KESHRI why did you take square root of (4/9) ?
• 9 years agoHelpfull: Yes(2) No(0)
• S1=20,S2=30.S2-S1=30-20=10km
• 10 years agoHelpfull: Yes(1) No(1)
• (s1/s2)=sqrt(t2/t1) this logic apliy where distance covered by is same but here after meeting they covered different distance and given time ie after meet time then how we applied these concet
• 7 years agoHelpfull: Yes(1) No(0)
• s1/s2==sqrt of (4/9)
  s1/s2=2/3
  s1=(2/3)*s2
  9s1+4s2=(2*300)
  9(2s2/3)+4s2=600
  6s2+4s2=600
  Thus, s2=60
  since s1=2s2/3
  s1=40
  Difference: 60-40=20km/hr
• 7 years agoHelpfull: Yes(0) No(5)