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Two trains of equal length take 10 seconds and 15 seconds respectively to cross a telegraph post. If the length of each train be 120 metres, in what time (in seconds) will they cross each other travelling in opposite direction ?
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- 16
- 15
- 12
- 10
Correct Option: C
When a train crosses a telegraph post, it covers its own length.
| ∴ Speed of first train = | = 12 m/sec. | |
| 10 |
| Speed of second train = | = 8 m/sec. | |
| 15 |
Relative speed = 12 + 8 = 20 m/sec.
| Required time = | |
| Relative Speed |
| = | = 12 seconds. | |
| 20 |
