Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 20)
20.
A train moves past a telegraph post and a bridge 264 m long in 8 seconds and 20 seconds respectively. What is the speed of the train?
Answer: Option
Explanation:
Let the length of the train be x metres and its speed by y m/sec.
| Then, | x | = 8  x = 8y |
| y |
| Now, | x + 264 | = y |
| 20 |
8y + 264 = 20y
y = 22.
 Speed = 22 m/sec = |
 |
22 x | 18 |  |
km/hr = 79.2 km/hr. |
| 5 |
Discussion:
46 comments Page 5 of 5.
Vamsy said:
1 decade ago
@Hussaian.
1) km/hr to m/s conversion:
km/hr = a x 5km/18hr.
2) m/s to km/hr conversion:
m/s = a x 18km/5hr.
1) km/hr to m/s conversion:
km/hr = a x 5km/18hr.
2) m/s to km/hr conversion:
m/s = a x 18km/5hr.
Anjani said:
10 years ago
Why we take 8 sec why don't we consider 20 sec?
Rahaman Khan said:
10 years ago
1) Train cross the pole in 8 sec.
Speed = Distance/Time.
Assume the train speed is x and length of train be y.
x = y/8 or y = 8x.
2) Train cross the bride which is 264mts long 20 sec.
x = (264+y)/20.
20x = 264+8x because y = 8x in above.
Solving the above equation we get speed is 22m/sec.
Finally convert the m/sec to km/hr.
22*18/5 = 79.2 km/hr.
Speed = Distance/Time.
Assume the train speed is x and length of train be y.
x = y/8 or y = 8x.
2) Train cross the bride which is 264mts long 20 sec.
x = (264+y)/20.
20x = 264+8x because y = 8x in above.
Solving the above equation we get speed is 22m/sec.
Finally convert the m/sec to km/hr.
22*18/5 = 79.2 km/hr.
Priya said:
1 decade ago
Hi, I didn't understand the solution. Can someone explain step by step ?
Jamir said:
9 years ago
Relative time = 20 - 8
= 12
Then,
Speed = Distance/ time
= 264/12
= 22 m/sec
= 22 *15/5 km/h.
= 79.2 km/ h.
Answer = 79.2 km/ h.
= 12
Then,
Speed = Distance/ time
= 264/12
= 22 m/sec
= 22 *15/5 km/h.
= 79.2 km/ h.
Answer = 79.2 km/ h.
Sanchita said:
1 decade ago
Please explain sum one in simple method.
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