# Aptitude - Problems on Trains - Discussion

### Discussion :: Problems on Trains - Data Sufficiency 1 (Q.No.2)

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.

2.

 What is the length of a running train crossing another 180 metre long train running in the opposite direction? I. The relative speed of the two trains was 150 kmph. II. The trains took 9 seconds to cross each other.

 [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

Explanation:

Let the two trains of length a metres and b metres be moving in opposite directions at u m/s and v m/s.

 Time taken to cross each other = (a + b) sec. (u + v)

 Now, b = 180, u + v = 150 x 5 m/sec = 125 m/sec. 18 3

 9 = a + 180 (125/3)

a = (375 - 180) = 195 m.

 Aditi said: (Nov 30, 2010) what is 5/18 in (u+v)?

 Kapil said: (Dec 16, 2010) Relative speed,u+v = 150 km/hr we multiply it with 5/18 to convert it into m/sec u+v= 150*(5/18)

 Sanjay said: (Jun 17, 2012) @ADITI. 1 kilo is 1000. 1hour is 60s*60m=3600s. 1000/3600 = 5/18. If you multiply 5/18 to that value you can convert it in to m/s.

 Mukesh said: (Aug 9, 2016) Time is taken to cross each other 9 seconds given in the question. So we can put the value in that place in the formula.

 Soni said: (Nov 8, 2016) I am not getting this answer. Please explain it.

 Dilhara said: (Feb 19, 2017) What is u+v? Please explain it.

 Ramshya Fathima said: (May 16, 2017) How we take b=180? I don't understand please explain anyone to know the answer.

 Saumya said: (Aug 13, 2017) Relative speed means U-V but it is considering u+v. So, the given answer is wrong.

 Nur Alom said: (Aug 25, 2017) The relative speed for opposite direction is u+v not u-v.

 Naeem said: (Sep 19, 2017) @Dilhara. u+v relative speed in case of opp. direction. @Ramshya_Fathima b=180 is given in data. Check it.

 Sony Sharda said: (Mar 3, 2018) How we take b=180?

 Deepanshu said: (Jun 4, 2018) @Sony Sharda. B is the length of another train which is given in the question=180m.

 Jagannath said: (Sep 5, 2018) Length of the train = speed* time.

 Shweta said: (Jan 23, 2019) How come 125/3? Please explain.

 Sunitha said: (Mar 6, 2019) @All. When you multiply 150*5/18 then you will get 125/3.

 Thanushree Y R said: (Sep 26, 2019) I can't understand the solution of this problem. please anyone tell me in brief.