Aptitude - Problems on Trains
Exercise : Problems on Trains - General Questions
- Problems on Trains - Formulas
- Problems on Trains - General Questions
- Problems on Trains - Data Sufficiency 1
- Problems on Trains - Data Sufficiency 2
- Problems on Trains - Data Sufficiency 3
16.
A train travelling at a speed of 75 mph enters a tunnel 3
miles long. The train is 
mile long. How long does it take for the train to pass through the tunnel from the moment the front enters to the moment the rear emerges?
miles long. The train is mile long. How long does it take for the train to pass through the tunnel from the moment the front enters to the moment the rear emerges?Answer: Option
Explanation:
| Total distance covered |
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 Time taken |
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| = 3 min. |
17.
A train 800 metres long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 minute, then the length of the tunnel (in meters) is:
Answer: Option
Explanation:
| Speed = |  |
78 x | 5 |  |
m/sec | = | |
65 | |
m/sec. |
| 18 | 3 |
Time = 1 minute = 60 seconds.
Let the length of the tunnel be x metres.
| Then, | |
800 + x | |
= | 65 |
| 60 | 3 |
3(800 + x) = 3900
x = 500.
18.
A 300 metre long train crosses a platform in 39 seconds while it crosses a signal pole in 18 seconds. What is the length of the platform?
Answer: Option
Explanation:
| Speed = | |
300 | |
m/sec = | 50 | m/sec. |
| 18 | 3 |
Let the length of the platform be x metres.
| Then, | |
x + 300 | |
= | 50 |
| 39 | 3 |
3(x + 300) = 1950
x = 350 m.
19.
A train speeds past a pole in 15 seconds and a platform 100 m long in 25 seconds. Its length is:
Answer: Option
Explanation:
Let the length of the train be x metres and its speed by y m/sec.
| Then, | x | = 15 y = |
x | . |
| y | 15 |
|
x + 100 | = | x |
| 25 | 15 |
15(x + 100) = 25x
15x + 1500 = 25x
1500 = 10x
x = 150 m.
20.
A train moves past a telegraph post and a bridge 264 m long in 8 seconds and 20 seconds respectively. What is the speed of the train?
Answer: Option
Explanation:
Let the length of the train be x metres and its speed by y m/sec.
| Then, | x | = 8 x = 8y |
| y |
| Now, | x + 264 | = y |
| 20 |
8y + 264 = 20y
y = 22.
| Speed = 22 m/sec = |
|
22 x | 18 | |
km/hr = 79.2 km/hr. |
| 5 |
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