Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 12)

Problems on Trains

12.

A goods train runs at the speed of 72 kmph and crosses a 250 m long platform in 26 seconds. What is the length of the goods train?

230 m

240 m

260 m

270 m

Answer: Option

Explanation:

Speed =		72 x	5	m/sec	= 20 m/sec.
			18

Time = 26 sec.

Let the length of the train be x metres.

Then,	x + 250	= 20
	26

x + 250 = 520

x = 270.

Discussion:

39 comments Page 1 of 4.

Nisha dahiya said: 1 decade ago

Why 72 is multiplied by 5/18?

Sania said: 1 decade ago

@ NISHA

Speed is given 72 kmps. But length of platform is in meters. so we have to change it into m/s.

Sonam said: 1 decade ago

Ya. But why only 5/18 why not some other numbers?

Dinesh guptha said: 1 decade ago

Hi sonam,
Let me explain about converting km/hr into m/s in detail.

1 km = 1000 meters.
1 hr = 3600 seconds.

1 km/hr = 1000/3600 m/s

= 10/36 m/s

= 5/18 m/s.

Therefore 1 km/hr = 5/18 m/sec.

(1)

Donald Pinto said: 1 decade ago

Hi Dinesh Thankyou so much for the explanation!!

Ashok.K.Rathod said: 1 decade ago

Thanks dinesh.

Sonia said: 1 decade ago

why x+250?.....for same direction we take sbtraction....then why it is added?

Yogesh said: 1 decade ago

x + 250 = 520, how 520 has come, please explain.

Savi said: 1 decade ago

Hi @Yogesh the formula is length=speed*time
here l=x*250
speed=72*5/18=20ms
time=26s
Apply formula
x+250=20*26
=520
Now got it

Akber said: 1 decade ago

@Sania.

Here platform is stationary that is the reason we are adding.

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