Two trains of length 150 m and 250m run on parallel lines. When they run in the same direction it will take 20 seconds to cross each other and when they run in opposite direction it will take 5 seconds. Find the speeds of the two trains.
a)180 and 108 b)272 and 211 c)123 and 828 d)none of these

• let speed of 1st train be x km/hr & second train be y km/hr. So equations will be
  (x-y)20=400 (becos trains are moving in same direction so speed get minus & total distance is sum of length of train).
  (x+y)5=400.
  Solve for x & y.
  value comes out to be x=50 km/hr = 180 m/sec & y= 30 km/hr = 108 m/sec.
  so ans is A)
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• a
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• 180 and 108
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• Why while using values in m/sec we considered them in km/hr and than again convert them to m/sec.
  400 is in meters and 20 is in seconds
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• The options are given in km/hr
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