Aptitude :: Problems on Trains

Practice :: Problems on Trains - General Questions
Problems on Trains - General Questions

Page Title 16. A train 800 m long is running at a speed of 78 km/h. What will be the length (in metres) of the tunnel, if it crosses a tunnel in 1 minute.
500 m
520 m
530 m
510 m
Answer: option A

Speed = (78 x 5/18) m/s. = 65/3 m/s.

Time = 1 minute = 60 seconds.

Let the length of the tunnel be x metres.

∵ Then, (800 + X/60) = 65/3

⟹ 3(800 + X) = 3900

⟹ X = 500 meters



17. A 300 meter long train crosses a platform in 39 seconds while it crosses a signal pole in 18 seconds. What is the length of the platform?
355 meter
350 meter
340 meter
345 meter
Answer: option B

Speed = 300/18 m/s. = 50/3 m/sec.

Let the length of the platform be x metres.

∵ Then, (X + 300/39) = 50/3

⟹ 3(x + 300) = 1950

⟹ x = 350 m.



18. A train crosses a telegraph post and a bridge 264 m long in 8 sec and 20 sec respectively. What is the speed of the train?
79.5 km/hr
80.2 km/hr
79.2 km/hr
75 km/hr
Answer: option C

Let the length of the train be X metres and its speed by Y m/sec.

Then, X/Y = 8

⟹ X = 8Y

Now, (X + 264/20) = Y

⟹ 8Y + 264 = 20Y

⟹ Y = 22.

∵ Speed = 22 m/sec = (22 x 18/5) km/hr. = 79.2 km/hr.



19. How many seconds will a 500 meter long train pass a man traveling at the speed of 3 km/hr in the direction of the moving train, if the speed of the train is 63 km/hr?
30 sec.
28 sec.
32 sec.
35 sec.
Answer: option A

Speed of the train relative to man = (63 - 3) km/hr

= 60 km/hr

= (60 x 5/18) m/sec.

= 50/3 m/sec

∵ Time taken to pass the man = (500 x 3/50) sec.

= 30 sec.



20. Two passenger trains each 500 m long, are running in opposite directions on parallel tracks. Their speeds are 45 km/hr and 30 km/hr respectively. Find the time taken by the slower train to pass the driver of the faster one.
30 sec
24 sec
29 sec
34 sec
Answer: option B

Relative speed = = (45 + 30) km/hr

= (75 x 5/18) m/sec.

= 125/6 m/sec.

We have to find the time taken by the slower train to pass the DRIVER of the faster train and not the complete train.

So, distance covered = Length of the slower train.

Therefore, Distance covered = 500 m.

∵ Required time = (500 x 6/125) = 24 sec.




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