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Two rifles are fired from the same place at a difference of 11 min. 45 seconds. But a man who is coming towards the same place in a train hears the second sound after 11 minutes. Find the speed of the train (Assuming speed of sound = 330 m/s).
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- 72 km/h
- 36 km/h
- 81 km/h
- 108 km/h
Correct Option: C
Difference of time = 11 minutes 45 seconds – 11 minutes = 45 seconds
Distance covered by sound in 45 seconds = Distance covered by train in 11 minutes
⇒ 330 × 45 = 11 × 60 × Speed of train
| ⇒ Speed of train = |  |  | m/sec. | |
| 11 × 60 |
| = | | × | | kmph. | ||
| 2 | 5 |
= 81 kmph.
