Two trains each having a length of 160 meters moving in opposite direction crossed each other in 9 seconds. If one train crossed a 200-metre-long platform in 18 seconds,then the ratio of their speeds is:
Answer & explanation
Correct answer: option 2
Train take 18 seconds to cross 200 m long platform ,
So Speed of train = \(\frac{200 + 160 }{18}\)
= \(\frac{360 }{18}\) = 20 m/sec
Let Speed of another train = A km/h
Relative speed when they moves in opposite direction = ( 20 + A ) km/h
Distance covered = 160 + 160 = 320 m
Time = 9 sec
Speed = \(\frac{320 }{9}\)
( 20 + A ) = \(\frac{320 }{9}\)
180 + 9A = 320
A = \(\frac{140 }{9}\)
Ratio of their speed is , 20 : \(\frac{140 }{9}\)
= 9 : 7