SOLUTION: Two stations A and B on a railway line are 144 kilometers apart. A fast train starts from B at 9 a.m., another fast train travelling at the same speed starts from A at 10 a.m. A sl
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Question 681848: Two stations A and B on a railway line are 144 kilometers apart. A fast train starts from B at 9 a.m., another fast train travelling at the same speed starts from A at 10 a.m. A slow train starts from B at 10:20 a.m., the fast train A meets the other fast train at 11:30 a.m., and the slow train at 12:32 p.m. When does the slow train reach A? Answer by sachi(548) (Show Source):
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Two stations A and B on a railway line are 144 kilometers apart
both the fast trains travel at same speed say s km/hr towards each other
& met at 11:30 a.m i.e after 2hrs 30 mins =2.5 hr
so the distance travelled in 2.5hrs by both trains =2.5*2*skm=5s km (as travelling towards each other)
so obviously 5s=144 km (as both are meeting)
so s=144/5 km/hr=28.8 km/hr
now let us consider the slow train which meets the fast train at 12.32 pm i.e.after 2hrs & 32 mins=2+32/60 hr=2.53 hrs
the distance travelled by fast train in 2.53hrs=28.8*2.53=72.96=73 km (approx)
so the dist travelled by the slow train=144-73=71 kms
this distance was travelled by the slow train in 12.32-10.20=2hrs 12min=2.2 hrs
now the speed of the slow train=71/2.2=32.27 km/hr
so thetime taken by the slow train to travel 144 kms=144/32.27=4.46hrs
=4hrs 27.7min =4hrs & 28 mins (approx)
so the time of reaching of the slow train=10.20+4hrs 27min=14hrs & 47min
=2.47pm
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