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 5 of 5.
Amit Kumar Verma said:
2 years ago
By solving the value of the speed of the train (u) is 101/3 and this doesn't satisfy statement 1.
So how the answer will be? Please explain me.
So how the answer will be? Please explain me.
(2)
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)
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)
Nisha Thakkar said:
9 months ago
@All.
We can directly find the speed of the first train by using the formula speed of the first train = relative speed + speed of the second train.
So, statement B alone is sufficient, therefore option B is right.
We can directly find the speed of the first train by using the formula speed of the first train = relative speed + speed of the second train.
So, statement B alone is sufficient, therefore option B is right.
(1)
ANUSREE said:
3 months ago
Hi all.
I also first doubted that the 2nd alone is enough to find speed. But now I realise that the length of the train is given in 1st statement and we can’t find the speed without that length.
Hence, E is the correct option.
I also first doubted that the 2nd alone is enough to find speed. But now I realise that the length of the train is given in 1st statement and we can’t find the speed without that length.
Hence, E is the correct option.
(1)
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