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A train passes by a lamp post on a platform in 7 sec. and passes by the platform completely in 28 sec. If the length of the platform is 390 m, then length of the train (in metres) is
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- 120
- 130
- 140
- 150
Correct Option: B
Let the length of train be x metre, then
| ∴ Speed of train = | = | ||
| 7 | 28 |
| ⇒ x = | |
| 4 |
⇒ 4x – x = 390
| ⇒ x = | = 130 metres | |
| 3 |
