Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - Data Sufficiency 2 (Q.No. 1)
Directions to Solve
Each of the questions given below consists of a question followed by three statements. You have to study the question and the statements and decide which of the statement(s) is/are necessary to answer the question.
1.
What is the speed of the train? | |
I. | The train crosses a signal pole in 18 seconds. |
II. | The train crosses a platform of equal length in 36 seconds. |
III. | Length of the train is 330 metres. |
Answer: Option
Explanation:
Let the speed of the train be x metres/sec.
| Time taken to cross a signal pole = | Length of the train |
| Speed of the train |
| Time taken to cross a platform = | (Length of the train + Length of the Platform) |
| Speed of the train |
Length of train = 330 m.
| I and III give, 18 = | 330 |  x = |
330 | m/sec = | 55 | m/sec. |
| x | 18 | 3 |
| II and III give, 36 = | 2 x 330 | x = |
660 | m/sec = | 55 | m/sec. |
| x | 36 | 3 |
Correct answer is (D).
Discussion:
20 comments Page 1 of 2.
Anchal said:
6 years ago
The answer must be E.
If used 1 and 2 only. Then their velocities are equal and hence after finding the value of train length easily speed can be found out.
If used 1 and 2 only. Then their velocities are equal and hence after finding the value of train length easily speed can be found out.
(4)
Ganadakshaka.k said:
5 years ago
As statement 1 and 3 can be used because time and train length is given calculated by this formula:t = l/s.
And 2 and 3 can be used because of the same reason t=2*l/s, 2is multiplied because in question they have given train and platform length are same.
So, answer D is correct.
And 2 and 3 can be used because of the same reason t=2*l/s, 2is multiplied because in question they have given train and platform length are same.
So, answer D is correct.
(2)
Shubham said:
8 years ago
Guys, who are saying statement 1 and 2 is also sufficient. Kindly, solve it once, you will see, both LHS and RHS will come out equal, and we won't get any result. That's why statement 3 and any of statement 1 or 2 is the right answer.
(2)
Sri said:
6 years ago
I think both the length of the train and platform is 330 so did 2*330.
(1)
Arun said:
6 years ago
Why 330 is multiplied by 2?
(1)
Anksuh said:
6 years ago
@All.
By comparing 1 & 2 speed becomes length/18 in both cases so we can't solve them. Therefore given option is correct.
By comparing 1 & 2 speed becomes length/18 in both cases so we can't solve them. Therefore given option is correct.
(1)
Narayana Bojja said:
8 years ago
No, the correct answer is E. Because we can use statements I, II to determine train speed.
Neha Priya said:
7 years ago
Either 2 can be used but only 3 cannot give the speed of train so, the answer should be E.
Manoj said:
7 years ago
Why 330 is multiplied by 2?
Fiza said:
8 years ago
Yes, the answer is D. Thanks @Shubham.
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