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Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - Data Sufficiency 1 (Q.No. 1)
Problems on Trains
Directions to Solve

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.
1.

What is the speed of the train whose length is 210 metres?

I. 

The train crosses another train (Howrah Express/12869) of 300 metres length running in opposite direction in 10 seconds.

 II. 

The train crosses another train (Howrah Express/12869) running in the same direction at the speed of 60 km/hr in 30 seconds.

I alone sufficient while II alone not sufficient to answer
II alone sufficient while I alone not sufficient to answer
Either I or II alone sufficient to answer
Both I and II are not sufficient to answer
Both I and II are necessary to answer
Answer: Option
Explanation:

Time taken to cross the train,
running in opposite directions		 = (l1 + l2) sec.
(u + v)

10 = (210 + 300)
(u + v)

   u + v = 51.

Time taken to cross the train, running in same direction = (l1 + l2) sec.
(u - v)

30 = (210 + 300)
(u - 60 x (5/18))

u = 17 + 50 m/sec.
3

Thus, u and v can be obtained.

Correct answer is (E).

Discussion:
45 comments Page 2 of 5.
Amit Kumar said:   6 years ago
Anuj it will take 0.02 hours to cross the Bridge.
(1)
Akash C P said:   6 years ago
We are not using the relation u+v=51 to find the final answer so statement 2 alone is sufficient, option B is right.
(6)
Mandal said:   6 years ago
How is statement 2 sufficient? can anyone explain it in details that only statement 2 is sufficient?
(1)
Vinayak N Kamath said:   6 years ago
As they have asked about the speed of train that is 210m long. So data 2 is sufficient to answer.
Shanthkumar said:   6 years ago
Considering the direction of trains as per statement 1 i.e. opposite direction and statement 2 i.e the same direction so we need both statements to find train speed in both directions respectively.
Utkarsh saxena said:   7 years ago
Option E is correct because the length of the second train that is 300 m is given in statement 1 without it you cannot find the answer.
Rathod said:   7 years ago
u=606/5 not (17+50/3=101/3 it is not right).
Sakshi Amrutkar said:   7 years ago
In the above given question where the length of a train is mentioned? please explain about it.
Pankaj said:   7 years ago
Agree @A. Srikanth &@ditya. I miss length of the 2nd train. Thanks.
Dhanupatil said:   7 years ago
V in sec, how it is (5/18)?
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