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.
Sweta said:
7 years ago
Hi, Can anyone tell me, what is the basic difference between Relative and Average speed?
(2)
Sumithra said:
7 years ago
For m/sec to km/hr conversion, we need to multiply with 18/5 only know.
Then why here it is multiplied with 5/18.
Then why here it is multiplied with 5/18.
(2)
Rahul said:
7 years ago
Thanks for explaining the solution @Swapnil.
Sanjeev said:
7 years ago
Can't understand. Please explain me in detail.
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.
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.
San said:
8 years ago
How distance and speed are equal here?
Mpa said:
8 years ago
How does distance can be equal?
Pooja said:
8 years ago
Nice explanation, Thanks @Sathees.
Priyanka said:
8 years ago
Why equating both distances?
Please explain me.
Please explain me.
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