Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - Data Sufficiency 1 (Q.No. 3)
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.
3.
What is the length of a running train? | |
I. | The train crosses a man in 9 seconds. |
II. | The train crosses a 240 metre long platform in 24 seconds. |
Answer: Option
Explanation:
| Time taken by train to cross a man = | Length of train |  Speed = |
l | ....(i) |
| Speed of train | 9 |
| Time taken by train to cross a platform = |
(Length of train + Length of platform) |
Speed = |
l + 240 | ....(ii) |
| Speed of train | 24 |
| From (i) and (ii), we get | l | = | l + 240 | . |
| 9 | 24 |
Thus, l can be obtained. So both I and II are necessary to get the answer.
The correct answer is (E).
Discussion:
16 comments Page 1 of 2.
Babu said:
1 decade ago
Train is passing a man.
Obviously the length of train will be the same as the required distance to pass that man as man has no length.
9 sec to pass the man (given).
24 sec to travel 240 m (given).
So, speed = 240/24 = 10 m/s.
Hence, Length of train = Distance travelled in 9s = 9*10 = 90 m.
Obviously the length of train will be the same as the required distance to pass that man as man has no length.
9 sec to pass the man (given).
24 sec to travel 240 m (given).
So, speed = 240/24 = 10 m/s.
Hence, Length of train = Distance travelled in 9s = 9*10 = 90 m.
(2)
Ambika said:
1 decade ago
Ambika
Please any help me; I can't understand how it is possible , because here they didn't give any comment about speed . How can we equate both speeds (Man &Train). I think option D is correct. Anybody can understood please explain to me.
Please any help me; I can't understand how it is possible , because here they didn't give any comment about speed . How can we equate both speeds (Man &Train). I think option D is correct. Anybody can understood please explain to me.
Atul said:
7 years ago
How can we say the train crossing the man and the platform is same. Also, the speed is also same. If nothing is given how option E is correct. Please specify in the question if any assumption is to be made or not.
Sana said:
7 years ago
Man is stationary & speed of the train is same for passing both man and platform. Thatswhy we can equate the two equations and get the length. It comes to be 144 meters.
Linux said:
1 decade ago
Can you please explain what the answer to the equation is I chose option B on the premise that the length of the train is 10 m.
How would we solve the equation please?
How would we solve the equation please?
Ajay said:
1 decade ago
The speed of the train is given but nothing is mentioned about the speed of the man.
How can it be solved unless condition about the man is given?
How can it be solved unless condition about the man is given?
Somil kumar bhadula said:
3 years ago
@All.
Here is the answer.
l/9 = l + 240/24,
l/9 = 9(l+10),
l/9 = 9l + 90,
10l = 91.
L= 91/10.
L = 9.5.
So, Answer is 9.5.
Here is the answer.
l/9 = l + 240/24,
l/9 = 9(l+10),
l/9 = 9l + 90,
10l = 91.
L= 91/10.
L = 9.5.
So, Answer is 9.5.
(2)
Viresh said:
1 decade ago
Here same train is crossing both man n d platform so d speed ll b same in both d cases so optn E is correct
Sujata said:
7 years ago
How can we say that the speed of train to cross man and platform is same?
Please anyone explain?
Please anyone explain?
Prerana said:
1 decade ago
Speed of man is not mentioned. What if he is also moving with some speed. So answer should be D.
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