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A train travelling at 48 km/hr crosses another train, having half its length and travelling in opposite direction at 42 km/hr, in 12 seconds. It also passes a railway platform in 45 seconds. The length of the railway platform is
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- 200 m
- 300 m
- 350 m
- 400 m
Correct Option: D
Let the length of the train travelling at 48 kmph be x metres.
Let the length of the platform be y metres.
Relative speed of train
= (48 + 42) kmph
= | m./sec. | |
18 |
= 25 m./sec.
and 48 kmph
= | = | m./sec. | ||
18 | 3 |
According to the question,
x + | ||
= | 2 | |
= 12
⇒ | = 12 | |
2 × 25 |
⇒ 3x = 2 × 12 × 25 = 600
⇒ x = 200 m.
Also, | = 45 | |
40/3 |
⇒ 600 + 3y = 40 × 45
⇒ 3y = 1800 – 600 = 1200
⇒ y = | = 400 m. | |
3 |