Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 28)
28.
A train overtakes two persons walking along a railway track. The first one walks at 4.5 km/hr. The other one walks at 5.4 km/hr. The train needs 8.4 and 8.5 seconds respectively to overtake them. What is the speed of the train if both the persons are walking in the same direction as the train?
Answer: Option
Explanation:
| 4.5 km/hr = |  |
4.5 x | 5 |  |
m/sec = | 5 | m/sec = 1.25 m/sec, and |
| 18 | 4 |
| 5.4 km/hr = | |
5.4 x | 5 | |
m/sec = | 3 | m/sec = 1.5 m/sec. |
| 18 | 2 |
Let the speed of the train be x m/sec.
Then, (x - 1.25) x 8.4 = (x - 1.5) x 8.5
8.4x - 10.5 = 8.5x - 12.75
0.1x = 2.25
x = 22.5
 Speed of the train = |
|
22.5 x | 18 | |
km/hr = 81 km/hr. |
| 5 |
Discussion:
54 comments Page 2 of 6.
Kavi said:
9 years ago
In the answer, x is distance because speed * time, how come you say that x is speed?
John said:
9 years ago
@Saurav 5/18 is the common unit to convert speed by km/hr to m/s. But the question is distance calculated can't be equal because both the persons having different speed and most probably they can't be at the equal level or abreast.
Varun said:
8 years ago
Thank you @Sathees.
Arsh said:
9 years ago
Can anybody tell me the shortcut method because in entrance exam there is not much time to make and solve equations?
Priyanka said:
8 years ago
Why equating both distances?
Please explain me.
Please explain me.
Pooja said:
8 years ago
Nice explanation, Thanks @Sathees.
Mpa said:
8 years ago
How does distance can be equal?
San said:
8 years ago
How distance and speed are equal here?
PrasannKumar said:
8 years ago
@Priyanka.
Both are the distances of the train only to get the answer he equated.
Both are the distances of the train only to get the answer he equated.
Swapnil said:
7 years ago
Both equations is equated because, distance cover by train for both the person is same, ie. Length of the train.
So in solution calculate the distance cover by train (length of the train) for both the person from given data and then equated them. Because distance covered by train (length of the train) is same for both the person.
So in solution calculate the distance cover by train (length of the train) for both the person from given data and then equated them. Because distance covered by train (length of the train) is same for both the person.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers