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# A train 500 metres long is crossing a tunnel 5 kilometres long at a

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Senior Manager
Joined: 25 Dec 2018
Posts: 298
Location: India
Concentration: General Management, Finance
GMAT Date: 02-18-2019
GPA: 3.4
WE: Engineering (Consulting)
A train 500 metres long is crossing a tunnel 5 kilometres long at a  [#permalink]

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19 Apr 2019, 09:07
5
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Difficulty:

55% (hard)

Question Stats:

57% (02:09) correct 43% (02:28) wrong based on 35 sessions

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A train 500 metres long is crossing a tunnel 5 kilometres long at a speed of 30 kilometres per hour. What is the difference in the time in minutes for which all the passengers of the train are inside the tunnel and the time for which a particular passenger is inside the tunnel?

A. 1
B. 1.5
C. 2
D. 3
E. 5
Manager
Joined: 09 Nov 2015
Posts: 68
Re: A train 500 metres long is crossing a tunnel 5 kilometres long at a  [#permalink]

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19 Apr 2019, 22:51
The time that any one person is inside the tunnel is equal to the time taken by the train to travel the length of the tunnel which is (5/30)=1/6 hour=10 minutes.....(i)
The time that all the persons in the train are inside the tunnel is equal to the time taken by the train to travel the length of the tunnel plus the time it takes to travel it's own length which is equal to 10+(0.5*60/30)=11 minutes.
Difference:11-10=1. Ans: A
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Joined: 26 Oct 2010
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A train 500 metres long is crossing a tunnel 5 kilometres long at a  [#permalink]

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24 Apr 2019, 20:59
2
effatara

I came up with the same answer but with a different logic.

1) The Time that one passenger is inside the tunnel = time taken by that one passenger to cross the tunnel = 5/30 = 1/6 = 10 mins

2) The Time that all the passengers are inside the tunnel = time taken by the train to cross the tunnel AFTER the moment the entire train is inside the tunnel.

So the distance that the train has to cover = 5000m - 500m = 4500m

So, time taken = 4500 / (30,000/60) = 9 mins

Hence the difference is 1 min. Ans A.

Bunuel, VeritasKarishma, please let us know the logic behind each of our approaches.
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Joined: 19 Oct 2018
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A train 500 metres long is crossing a tunnel 5 kilometres long at a  [#permalink]

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25 Apr 2019, 00:32
Relative distance covered by train in reference to a person standing outside the train= 500m
speed of train= 30kmph or 50/6 m/s
Time taken= 500/(50/6)=60 sec or 1 min
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Joined: 24 Jul 2011
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Re: A train 500 metres long is crossing a tunnel 5 kilometres long at a  [#permalink]

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25 Apr 2019, 00:47
Top Contributor
mangamma wrote:
A train 500 metres long is crossing a tunnel 5 kilometres long at a speed of 30 kilometres per hour. What is the difference in the time in minutes for which all the passengers of the train are inside the tunnel and the time for which a particular passenger is inside the tunnel?

A. 1
B. 1.5
C. 2
D. 3
E. 5

Difference = length of train / speed of train = 0.5/30 hours = 1 minute.

Option (A).
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Re: A train 500 metres long is crossing a tunnel 5 kilometres long at a  [#permalink]

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25 Apr 2019, 04:55
mangamma wrote:
A train 500 metres long is crossing a tunnel 5 kilometres long at a speed of 30 kilometres per hour. What is the difference in the time in minutes for which all the passengers of the train are inside the tunnel and the time for which a particular passenger is inside the tunnel?

A. 1
B. 1.5
C. 2
D. 3
E. 5

Time for which one passenger is inside the tunnel (say sitting right in front) = Time taken by the front of train to reach from the entry of tunnel to the exit of tunnel (a distance of 5000 m)
= 5 km/30 kmph = 10 mins

Time for which all passengers are inside the tunnel = Time at which the train's front is 500 m inside the tunnel to the time the front takes to reach the exit (a distance of 4500 m)
= 4.5/30 = 9 min

Time diff = 1 min

Alternatively,

The difference between the two times is the time it takes the front of the train to reach from the tunnel's entry to 500 m inside the tunnel
= .5 km / 30 kmph = 1 min
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Karishma
Veritas Prep GMAT Instructor

Re: A train 500 metres long is crossing a tunnel 5 kilometres long at a   [#permalink] 25 Apr 2019, 04:55
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