Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 4)

Problems on Trains

Two trains running in opposite directions cross a man standing on the platform in 27 seconds and 17 seconds respectively and they cross each other in 23 seconds. The ratio of their speeds is:

1 : 3

3 : 2

3 : 4

None of these

Answer: Option

Explanation:

Let the speeds of the two trains be x m/sec and y m/sec respectively.

Then, length of the first train = 27x metres,

and length of the second train = 17y metres.

	27x + 17y	= 23
	x+ y

27x + 17y = 23x + 23y

4x = 6y

	x	=	3	.
	y		2

Discussion:

240 comments Page 17 of 24.

Ajit said: 2 decades ago

Dear rohit,

Your calculation right but this furmula use in every cases or limited case?

Anil Bhadani said: 9 years ago

Its very shortcut and its very simple.

27-23 = 4
23-17 = 6
so,4:6 = 2:3 or 3:2 also.

Narayan said: 1 decade ago

27            17
      23
23-17=6          27-23=4

Then ratio become 3:2

Nisha said: 2 decades ago

Hi friends .....

1 km =1000m
1 hr=3600s

So, km/hr = 1000/3600 = 5/18

It's clear.

Pobitro Ghosh said: 9 years ago

Relative time 1st train= 27-23=4,
second train= 23-17=6,
1st:2nd= 6:4=3:2,
Ans:3:2.

L.santhosh reddy said: 8 years ago

Here, they mentioned 23sec and17sec but in answer, they took it as 23m and 17m why?

Bhanu said: 2 decades ago

Take all x terms once side and why terms other side then subtract we get 4x = 6y.

Thavapriya A said: 2 years ago

How to solve the following step?

27x+17y =23x+23y.

Could anyone tell me please?

(24)

Azhagarsamy said: 1 decade ago

Simple @Anil.

4x = 6y.
Then x/y = 6/4.

x/y = 3/2.

Therefore the ratio is 3:2.

Kiran said: 2 decades ago

X+Y is speeds of 2trains and 27x+17y is length of trains
so lenth/speed=time

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