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 1 of 5.
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)
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!
Rashi said:
2 years ago
The first train crosses the 2nd train running at a speed of 60 kmph so we've to find you and hence we would be 60 kmph.
So, firstly we'll take for same direction of the train formula to equate as equation (i) and then another opposite direction formula to equate as equation (ii) then combine these 2 eqs.
We'll get to have both the statements required to find out you.
Hence (e) is the correct option because it needs both statements to evaluate the answer which is "u" i.e., the speed of the first train.
So, firstly we'll take for same direction of the train formula to equate as equation (i) and then another opposite direction formula to equate as equation (ii) then combine these 2 eqs.
We'll get to have both the statements required to find out you.
Hence (e) is the correct option because it needs both statements to evaluate the answer which is "u" i.e., the speed of the first train.
(3)
Sundar said:
1 decade ago
Since in both statement reveals that the another train is "Howrah Express/12869" and its length is 300 meters.
Therefore, we can find the answer with I and II.
If it is not specified (if not included the another trains details specifically), it may be different trains and different length. In this case, the answer will be "Both I and II are not sufficient to answer".
Hope this will help you a little bit.
Therefore, we can find the answer with I and II.
If it is not specified (if not included the another trains details specifically), it may be different trains and different length. In this case, the answer will be "Both I and II are not sufficient to answer".
Hope this will help you a little bit.
Atchukola Naresh said:
4 years ago
Since in both statement reveals that the another train is "Howrah Express/12869" and its length is 300 meters.
Therefore, we can find the answer with I and II.
If it is not specified (if not included the another trains details specifically) , it may be different trains and different length. In this case, the answer will be "Both I and II are not sufficient to answer".
Hope this will help you a little bit.
Therefore, we can find the answer with I and II.
If it is not specified (if not included the another trains details specifically) , it may be different trains and different length. In this case, the answer will be "Both I and II are not sufficient to answer".
Hope this will help you a little bit.
(4)
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.
Aditya Panchal said:
2 years ago
The train crosses another train (Howrah Express/12869) running in the same direction at the speed of 60 km/hr in 30 seconds.
Here, there is one mistake. By reading the above statement, we find that the first train is crossing the other train at 60 km/hr. And they have taken this speed as 2nd train! How is this possible?
Anyone, please clarify my doubt.
Here, there is one mistake. By reading the above statement, we find that the first train is crossing the other train at 60 km/hr. And they have taken this speed as 2nd train! How is this possible?
Anyone, please clarify my doubt.
(2)
Sourav Saha said:
1 decade ago
In the problem using statement I we can find out the sum of the speeds of both the train u+v=51 -- (1) and can't we use the speed of the second train i.e. 60 km/hr and replace it in equation 1?
The results are 103/3 by replacing. And 101/3 by following the method given in the site.
Why is this difference in the result?
The results are 103/3 by replacing. And 101/3 by following the method given in the site.
Why is this difference in the result?
Gautam Kumar said:
1 decade ago
I don't think that option E is right. According to me option D is correct. This is because in the option I & II given in question it is specially mentioned Train number & Train name i.e. Howrah Express 12869. Now what I want to say that the same train can't run in both same & opposite direction at one time.
A.srikanth said:
1 decade ago
What @Sunder said it is right.
And what @GAUTHM KUMAR said is just like he showing his sense of humor. The answer E is correct.
And coming to @Adithya.
With out knowing the length of second train how you are going to find speed of first train ?
And what @GAUTHM KUMAR said is just like he showing his sense of humor. The answer E is correct.
And coming to @Adithya.
With out knowing the length of second train how you are going to find speed of first train ?
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