Aptitude - Problems on Trains

6.

The speed of a train 150 m long is 50 kmph. How much time will it take to pass a platform 600 m long ?

Answer

Answer :

Option B

Explanation :


Speed = 50 x 5 18 m/sec = 125 9 m/sec
Required time = (600 + 150) (125/9) sec = 750 x 9 125 = 54 sec
7.

A train crosses a pole in 15 seconds, while it crosses a 100m long platform in 25 seconds. The length of the train is :

Answer

Answer :

Option C

Explanation :


Let the length of the train be x m. Then,
x 15 = (100 + x) 25
⇒ 25x = 1500 + 15x ⇒ 10x = 1500 ⇒ x = 150
Hence, the length of the train is 150 m.
8.

A train is running at the rate of 40 kmph. A man is going in the same direction parallel to the train at 25 kmph. If the train crosses the man in 48 seconds, the length of the train is :

Answer

Answer :

Option D

Explanation :


Relative speed = (40 − 25) kmph = 15 kmph = 15 x 5 18 m/sec = 25 6 m/sec
Length of the train = 25 6 x 48m = 200 m
9.

Two trains running in opposite directions at 36 kmph and 45 kmph cross each other in 20 seconds. If one train is 200 m long, the length of the other train is :

Answer

Answer :

Option C

Explanation :


Let the length of the other train be x m
Sum of their lengths = (200 + x)m.
Relative speed = (36 + 45) kmph = 81 kmph = 81 x 5 18 m/sec = 45 2 m/sec
(200 + x) (45/2) = 20 ⇒ 400 + 2x = 900 ⇒ 2x = 500 ⇒ x = 250
∴ Length of the other train is 250 m.
10.

Two goods trains each 500 m long, are running in opposite directions on parallel tracks. Their speeds are 45 kmph and 30 kmph respectively. The time taken by the slower train to pass the driver of the faster one is :

Answer

Answer :

Option C

Explanation :


Relative speed = (40 + 35) kmph = 75 kmph = 75 x 5 18 m/sec = 125 6 m/sec
Distance covered = (500 + 500)m = 1000 m
Required time = 1000 x 6 125 sec = 48 sec
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