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## Question

I was sitting in a subway station No. 12(toatal stations are 24).

On this line are several trains transporting passengers from staion(No. 1 ) till the end station( No. 24),then each train will continue the journey from side to side(both sides are connected together at each end).I noticed that after each 4 Minutes a train arrives this station from left side toward the right side,one minute later another train arrives the station but to the opposit direction,and so on.

If each train stays in each station exactly one minute( notice that the train at each end will make a curve and return back to that staion,just like a circle).

Howmany trains are there on this line?

## 55 answers to this question

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Each train moves in one minute intrval,that means:

stays one minute in each station.

The time needed between each two stations is one minute.

All trains move at the same time(all together,as if they are chained ).

The gape between them will stay fix.

At stations 1 and 24 it stays one minute,make an (one minute curve)reaching the same station,but at opposit direction.

If the first train was at station Number 1...so the second train should be at station Number 7(6min. interval)and so on.

The total number of the trains should be...8...

Thanks

Edited by wolfgang

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Sorry can you explain how train at 1 gets to 7 in 6 minutes if it takes 1 minute between stations and stops for 1 minute at each. By my workings that must be 6 minutes moving and 6 minutes stationery which is 12 not 6!

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Let the start position to be like this:

from left to right, a train in station 1, 7,13,19

from right to left, a train in station 24,18,12,and 6

I am at station number 12, there is a train which will stay one minute then will move to the right.

as it moves,all the trains will move at the same time,like this:

from left to right,2,8,14,20

from right to left,23,17,11,5

after another movement:

3,9,15,21

22,16,10,4

and so on...after 4 minutes,the train that was at 7 will reach 12 from left side,the next train which was at 18 will reach 12 from the right side( after 5 min.).

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Let the start position to be like this:

from left to right, a train in station 1, 7,13,19

from right to left, a train in station 24,18,12,and 6

I am at station number 12, there is a train which will stay one minute then will move to the right.

as it moves,all the trains will move at the same time,like this:

from left to right,2,8,14,20

from right to left,23,17,11,5

after another movement:

3,9,15,21

22,16,10,4

and so on...after 4 minutes,the train that was at 7 will reach 12 from left side,the next train which was at 18 will reach 12 from the right side( after 5 min.).

You stated in post #24 that the time between 2 stations is 1 minute and yet claim that a train and also stated that time in each station is 1 minute. This would mean that the train that just arrived at 7, must stay 1 minute and spend 1 minute moving before reaching station 8. Continuing this thought means that the train at seven cannot reach 12 in less than 10 minutes because there are 5, gaps between stations, 1 minute each, and 5 stops of 1 minute at stations 7,8,9,10 & 11. I agree with Trainspotterx that you have a major problem with your solution of 8 trains.

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Yes...you are right..

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