Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 5)
5.
A train passes a station platform in 36 seconds and a man standing on the platform in 20 seconds. If the speed of the train is 54 km/hr, what is the length of the platform?
120 m
240 m
300 m
None of these
Answer: Option
Explanation:

Speed = 54 x 5 m/sec = 15 m/sec.
18

Length of the train = (15 x 20)m = 300 m.

Let the length of the platform be x metres.

Then, x + 300 = 15
36

x + 300 = 540

x = 240 m.

Discussion:
276 comments Page 26 of 28.

Arun said:   1 decade ago
@divya :yeah... Its good..

Divya said:   1 decade ago
I solved in dis manner
54*(5/18)=15
speed =15m/sec
it crossed d platform within 36 secs
for 20 sec=?
36-20=16
16*15=240m

Satheesh said:   1 decade ago
Hi Guys

1 Km=1000 Meters
1 hr=3600 seconds

If the speed of the train is 54 km/hr
54*1000= 54000
54000/3600=15
A train passes a station platform in 36 seconds
15*36=540
a man standing on the platform in 20 seconds
15*20=300

540-300=240
Ans:240 Simple

Kranthi said:   1 decade ago
As they asked only platform length why isn't it 35X15=540...
why should we substract...??

Vivek said:   1 decade ago
speed:- 54*5/18= 15 m/sec
length of the train:-15*20= 300 m.(distance= speed * time)
length of the platform:-x

Speed = Distance /Time
15=300+x/36
300+x=540
x=540-300
x=240

Shelly said:   1 decade ago
Thanks Rahul.

Karthik said:   1 decade ago
Shortcut:

Minus the both time of the train to cross the platform as well as man (reference point).

T = 36 sec, t = 20 sec.

T - t = 16 sec.

With the normal formula Length = Speed * Time

(i.e) 15 m/s * 16 sec = 240 metres.

Magesh said:   1 decade ago
Guys listen.

Take a point as man standing on the platform. So the moving train pass the point at the time of 20 sec.

So, Length of the train = (15 x 20)m = 300 m.

Gaurang said:   1 decade ago
Amit thanks for answer correctly.

Remy said:   1 decade ago
How come (300+x) /15?its not said the man stands at the beginning of platform. If hes somwhere in the middle how come we add the length of the train 300 m ?


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