Latest GENPACT Aptitude Question SOLUTION: A train travelling at 48 kmph completely crosses another train having half its length and travelling in opposite direction at 42 kmph, in 12 seconds. It also passes a railway platf

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(#M40005043) GENPACT question Problem on trains Keep an EYE

A train travelling at 48 kmph completely crosses another train having half its length and travelling in opposite direction at 42 kmph, in 12 seconds. It also passes a railway platform in 45 seconds. The length of the platform is

A. 400 m
B. 450 m
C. 560 m
D. 600 m

Asked In GENPACT (12 years ago)

Unsolved Read Solution (4)

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Sanjana Patnaik  (12 years ago)

Length of the Ist train=2x m and the length of the other train be x m(1/2)
The relative speed of the train(48+42)=90kmph or 25m/s
Time taken to cross one another=12s
Hence, 12=2x+x/25
Solving, x=100m and 200m
Now to determine the length of the platform
45=100+length of the platform/speed of the Ist train
45=100+L/240/18( 48kmph=240/118m/s)

Solving, we get L=600M(option D)

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Ankitt Shrivastava  (9 years ago)

let the length of 1st train =x;
then length of second train=x/2
Speed of first train = 48kmph=(48*5/18=40/3msec)
Speed of second train = 42 kmph

because they are travelling in opposite dorection so their speed will be added hence
relative spedd = 48+42=90kmph
convert this in m/sec= 90*5/18=25m/sec.

Now, by formula Speed= Distance/Time, we have(Distance=length of 1st train+length of second train)
i.e. x+x/2
25=x+x/2/12
on solving, we get x=200(length of 1st train)
x/2=100 (length of 2nd train)

now, let the length of platform =y;
then Same formula:- Speed =distance/time (with respect to first train)
Speed= 48*5/18(for m/sec)=40/3m/sec.
now, put in formula
40/3=200+y/45

y=400. Ans

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prateek agarwal  (11 years ago)

Let the length of the first train be 2d metres.

Then, the length of the second train is ( ( metres.
2

Relative speed = (48 + 42) kmph = ( 90 x 5 ( m/sec = 25 m/sec.
18

Therefore [x + (x/2)] = 12 or 3x = 300 or x = 200.
25 2

Therefore Length of first train = 200 m.

Let the length of platform be y metres.

Speed of the first train = ( 48 x 5 ( m/sec = 40 m/sec.
18 3

Therefore (200 + y) x 3 = 45
40

=> 600 + 3y = 1800

=> y = 400 m.

Is this solution Helpfull? Yes (1) | No   

prateek agarwal  (11 years ago)

correct one -Let the length of the first train be x metres.

Then, the length of the second train is ( x ( metres.
2

Relative speed = (48 + 42) kmph = ( 90 x 5 ( m/sec = 25 m/sec.
18

Therefore [x + (x/2)] = 12 or 3x = 300 or x = 200.
25 2

Therefore Length of first train = 200 m.

Let the length of platform be y metres.

Speed of the first train = ( 48 x 5 ( m/sec = 40 m/sec.
18 3

Therefore (200 + y) x 3 = 45
40

=> 600 + 3y = 1800

=> y = 400 m.

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