Aptitude Problems On TrainsPage 2
9. | | A train covers a distance of 12 km in 10 min. If it takes 8 seconds to pass a telegraph post, then the length of the train is: | | (a)180 m | | (b)100 m | | (c)160 m | | (d)140 m |
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Answer is: CSpeed = (12/10) x 60 kmph = (72 x 5/18) m/s = 20 m/s
Length of the train = (Speed x Time) = (20 x 8) m = 160 m
10. | | The length of the bridge, which a train 230 meters long and travelling at 45 kmph can cross in 30 seconds, is: | | (a)200 m | | (b)145 m | | (c)245 m | | (d)350 m |
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Answer is: BSpeed = (45 x 5/18)m/s = (25/2)m/s.
Time = 30 sec
Let the length of bridge be X metres.
Then, (230 + X)/30 = 25/2
⇒ 2(230 + X) = 750
⇒ X = 145 m.
11. | | A goods train runs at the speed of 72 kmph and crosses a 270 m long platform in 26 seconds. What is the length of the goods train? | | (a)250 m | | (b)220 m | | (c)260 m | | (d)240 m |
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Answer is: ASpeed = (72 x 5/18)m/s = 20 m/s.
Time = 26 sec
Let the length of the train be X metres.
Then, (X + 270)/26 = 20
⇒ X + 270 = 520
⇒ X = 250.
12. | | A 300 m long train crosses a platform in 42 seconds while it crosses a signal pole in 18 seconds. What is the length of the platform? | | (a)350 m | | (b)400 m | | (c)650 m | | (d)Data inadequate |
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Answer is: BSpeed = (300/18) m/sec = 50/3 m/sec.
Let the length of the platform be X metres.
Then, (X + 300)/42 = 50/3
⇒ 3(X + 300) = 2100
⇒ X = 400 m.
13. | | A train speeds past a pole in 20 seconds and a platform 100 m long in 30 seconds. Its length is: | | (a)250 m | | (b)150 m | | (c)180 m | | (d)200 m |
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Answer is: DLet the length of the train be X metres and its speed by Y m/sec.
They, X/Y = 20
⇒ Y = X/20
∴ (X + 100)/30 = X/20
⇒ X = 200 m.
14. | | A train moves past a telegraph post and a bridge 276 m long in 8 seconds and 20 seconds respectively. What is the speed of the train? | | (a)80.5 kmph | | (b)71 kmph | | (c)78.2 kmph | | (d)82.8 kmph |
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Answer is: DLet the length of the train to be X metres and speed by Y m/s.
They, X/Y = 8
⇒ X = 8Y
Now, (X + 276/)20 = Y
⇒ 8Y + 276 = 20Y
⇒ Y = 23
∴ Speed = 23 m/s = (23 x 18/5)mph = 82.8 kmph.
15. | | How many seconds will a 500 m long train take to cross a man walking with a speed of 8 kmph in the direction of the moving train if the speed of the train is 68 kmph? | | (a)32 | | (b)30 | | (c)34 | | (d)35 |
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Answer is: BSpeed of train relative to man = (68 - 8) kmph = 60 kmph.
Speed of train relative to man = (60 x 5/18) m/s = 50/3 m/sec.
∴ Time taken to pass man = (500 x 3/50) sec = 30 sec.
16. | | Two trains are moving in opposite directions at the speed of 80 kmph and 110 kmph. Their lengths are 1.20 km and 0.8 km respectively. The time taken by the slower train to cross the faster train in seconds is: | | (a)36 | | (b)36.8 | | (c)37.8 | | (d)39 |
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Answer is: CRelative speed = (80 + 110) kmph = 190(5/18) m/s = 475/9 m/s.
Distance covered = (1.20 + 0.8) km = 2 km = 2000 m.
∴ Required time = 2000 x (9/475) = 37.8 seconds
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