Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - Data Sufficiency 1 (Q.No. 1)
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. |
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 3 of 5.
Priyanka said:
8 years ago
I think statement 2 is sufficient.
Kriti said:
8 years ago
Option (B) is the correct answer since statement II alone is sufficient to find the answer.
Anuj said:
9 years ago
Actually, I have a doubt on this question a tree and having a length of 350 metre cross the bridge length 750 m. If the speed of the train is 55 kilometre per hour how much time will the train take to cross the bridge?
Can anyone solve this?
Can anyone solve this?
Hari said:
9 years ago
Only statement ii is sufficient to find the speed of the train asked in question but the statement I gives the length of the train. So we are using the length of train specified in statement I and substituting in statement II. So if statement I is not given we don't know the length of the train which we will substitute in statement II as per below.
Based on statement II.
Time taken to cross the train, running in same direction = (l1 + l2) / (u - v) (l1=given in question; l2= given in statement II; v= given in statement II; u = speed of train).
30 = (210 + 300) / (u - 60 x (5/18) ).
u = (17 +50/3) which is the speed of train asked in the question.
Therefore E is the correct answer.
Based on statement II.
Time taken to cross the train, running in same direction = (l1 + l2) / (u - v) (l1=given in question; l2= given in statement II; v= given in statement II; u = speed of train).
30 = (210 + 300) / (u - 60 x (5/18) ).
u = (17 +50/3) which is the speed of train asked in the question.
Therefore E is the correct answer.
(2)
Vidhya said:
9 years ago
Yes, you are right @Gautam Kumar.
Shubham said:
9 years ago
Statement 2 is sufficient.
M.Homesh said:
9 years ago
We can also solve it by using the relative speed method.
S1 + S2 = D1/T.
S1 + S2 = D1/T.
Udita Mandal said:
10 years ago
Hi, I think correct answer is 'B' because according to the question we have to find out only speed of train with length 210 m i.e. 'u', which can be satisfactorily found out by the information given in option 2, there is no need of finding value of 'v', and none of information given in option 1 is helpful in finding out the answer.
So correct answer according to me is 'B' only option 2 is sufficient to answer the given question. Please go through my suggestion and if I am wrong then correct my doubt.
Thank you!
So correct answer according to me is 'B' only option 2 is sufficient to answer the given question. Please go through my suggestion and if I am wrong then correct my doubt.
Thank you!
Utsav Bansal said:
1 decade ago
Option E is okay, just see the instruction guys both statements together are necessary to answer this question as from stat-1 you will get the length of other train n using stat-2 data you can calculate the speed easily, one thing that I find ambiguous is that both statements are contradicting as in 1st one train is moving in opposite direction while in 2nd one same train is moving in same direction.
Lokesh said:
1 decade ago
Please anyone explain me. I think the answer is 'D' but it was 'E'. Why?
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