Aptitude - Problems on Trains - Discussion

Each of the questions given below consists of a statement and / or a question and two statements numbered I and II given below it. You have to decide whether the data provided in the statement(s) is / are sufficient to answer the given question. Read the both statements and

  • Give answer (A) if the data in Statement I alone are sufficient to answer the question, while the data in Statement II alone are not sufficient to answer the question.
  • Give answer (B) if the data in Statement II alone are sufficient to answer the question, while the data in Statement I alone are not sufficient to answer the question.
  • Give answer (C) if the data either in Statement I or in Statement II alone are sufficient to answer the question.
  • Give answer (D) if the data even in both Statements I and II together are not sufficient to answer the question.
  • Give answer(E) if the data in both Statements I and II together are necessary to answer the question.

3. 

What is the length of a running train?

I. 

The train crosses a man in 9 seconds.

 II. 

The train crosses a 240 metre long platform in 24 seconds.

[A]. I alone sufficient while II alone not sufficient to answer
[B]. II alone sufficient while I alone not sufficient to answer
[C]. Either I or II alone sufficient to answer
[D]. Both I and II are not sufficient to answer
[E]. Both I and II are necessary to answer

Answer: Option E

Explanation:

Time taken by train to cross a man = Length of train       Speed = l ....(i)
Speed of train 9

Time taken by train
to cross a platform =
(Length of train +
Length of platform)
     Speed = l + 240 ....(ii)
Speed of train 24

From (i) and (ii), we get l = l + 240 .
9 24

Thus, l can be obtained. So both I and II are necessary to get the answer.

The correct answer is (E).


Ambika said: (Dec 25, 2010)  
Ambika
Please any help me; I can't understand how it is possible , because here they didn't give any comment about speed . How can we equate both speeds (Man &Train). I think option D is correct. Anybody can understood please explain to me.

Viresh said: (Mar 18, 2011)  
Here same train is crossing both man n d platform so d speed ll b same in both d cases so optn E is correct

Prerana said: (Oct 21, 2013)  
Speed of man is not mentioned. What if he is also moving with some speed. So answer should be D.

Yogitha said: (Jun 30, 2014)  
Please give some instruction about train problems?

Linux said: (Nov 11, 2014)  
Can you please explain what the answer to the equation is I chose option B on the premise that the length of the train is 10 m.

How would we solve the equation please?

Ajay said: (Nov 19, 2014)  
The speed of the train is given but nothing is mentioned about the speed of the man.

How can it be solved unless condition about the man is given?

Nithyasri said: (Feb 9, 2015)  
It's possible? I can't get it. Anyone else explain it.

Babu said: (Sep 11, 2015)  
Train is passing a man.

Obviously the length of train will be the same as the required distance to pass that man as man has no length.

9 sec to pass the man (given).

24 sec to travel 240 m (given).

So, speed = 240/24 = 10 m/s.

Hence, Length of train = Distance travelled in 9s = 9*10 = 90 m.

Hernando said: (Oct 9, 2015)  
Answer should be D. No reason to assume the same speed of the train in both cases.

Nadeem said: (Jul 29, 2017)  
How 1st statement is true? Explain.

Sana said: (Dec 15, 2018)  
Man is stationary & speed of the train is same for passing both man and platform. Thatswhy we can equate the two equations and get the length. It comes to be 144 meters.

Atul said: (Feb 3, 2019)  
How can we say the train crossing the man and the platform is same. Also, the speed is also same. If nothing is given how option E is correct. Please specify in the question if any assumption is to be made or not.

Sujata said: (Feb 28, 2019)  
How can we say that the speed of train to cross man and platform is same?

Please anyone explain?

Post your comments here:

Name *:

Email   : (optional)

» Your comments will be displayed only after manual approval.