Aptitude - Problems on Trains
1.
A 180 m long train takes 15 seconds to cross a man standing on a platform. The speed of the train is :
Answer
Speed = 180 15 m/sec = 12 m/sec
Answer :
Option BExplanation :
Speed = 180 15 m/sec = 12 m/sec
2.
A train travelling at a speed of 30 m/sec crosses a platform 600 m long in 30 seconds. The length of the train is :
Answer
Let the length of the train be x m. Then, its speed =
(600 + x)
30
m/sec
∴
(600 + x)
30
= 30
⇒ 600 + x = 900
⇒ x = 300
Answer :
Option DExplanation :
Let the length of the train be x m. Then, its speed =
(600 + x)
30
m/sec
∴
(600 + x)
30
= 30
⇒ 600 + x = 900
⇒ x = 300
3.
A train 270 m long is moving at a speed of 25 kmph. It will cross a man coming from the opposite direction at a speed of 2 kmph in
Answer
Their relative speed = (25 + 2) kmph = 27 kmph =
27 x 5 18 
m/sec = 7.5 m/sec
Required time = 270 7.5 sec = 36 sec
Answer :
Option AExplanation :
Their relative speed = (25 + 2) kmph = 27 kmph =
27 x 5 18 m/sec = 7.5 m/sec Required time = 270 7.5 sec = 36 sec
4.
Two trains, one from station A to station B and the other from B to A start simultaneously. After meeting, the trains reach their destinations after 9 hours and 16 hours respectively. The ratio of their speed is :
Answer
A's speed : B's speed = √b : √a = √16 : √9 = 4 : 3
Answer :
Option BExplanation :
A's speed : B's speed = √b : √a = √16 : √9 = 4 : 3
5.
A train 125 m long is running at 50 kmph. In what time will it pass a man, running at 5 kmph in the same direction in which the train is going ?
Answer
Speed of the train relative to man = (50 − 5) kmph = 45 kmph
=45 x 5 18 m/sec = 12.5 m/sec
Distance covered in passing the man = 125 m.
∴ Time taken = 125 12.5 sec = 10 sec
Answer :
Option BExplanation :
Speed of the train relative to man = (50 − 5) kmph = 45 kmph
=
45 x 5 18 m/sec = 12.5 m/sec Distance covered in passing the man = 125 m.
∴ Time taken = 125 12.5 sec = 10 sec
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