Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 19)
19.
A train speeds past a pole in 15 seconds and a platform 100 m long in 25 seconds. Its length is:
Answer: Option
Explanation:
Let the length of the train be x metres and its speed by y m/sec.
| Then, | x | = 15  y = |
x | . |
| y | 15 |
 |
x + 100 | = | x |
| 25 | 15 |
15(x + 100) = 25x
15x + 1500 = 25x
1500 = 10x
x = 150 m.
Discussion:
55 comments Page 4 of 6.
Anishghoshroy said:
1 decade ago
Let the speed of the train be x.
Then, the length of the train is 15x.
Therefore, 100+15x = 25x.
x = 10.
Which mean the speed of the train is 10 m/s as assumed above.
Then the length of train is 150 m.
Then, the length of the train is 15x.
Therefore, 100+15x = 25x.
x = 10.
Which mean the speed of the train is 10 m/s as assumed above.
Then the length of train is 150 m.
Amit said:
1 decade ago
Why 25-10?
S Madhukar said:
1 decade ago
Speed = Length/Time.....(1).
Distance = Speed*Time.....(2).
Time = Higher time - Lower time.
= 25-15 = 10.
Distance = 100 given.
100 = Speed*10.
Speed = 10 substitute in equation (1).
Length = 10*15 = 150.
Distance = Speed*Time.....(2).
Time = Higher time - Lower time.
= 25-15 = 10.
Distance = 100 given.
100 = Speed*10.
Speed = 10 substitute in equation (1).
Length = 10*15 = 150.
Vinay kumar said:
1 decade ago
Speed*Time = Distance.
S*T = D.
T = 25-15 = 10.
S = D/t = x/15, x = length of train.
(x/15)*10 = 100.
x = 150m.
S*T = D.
T = 25-15 = 10.
S = D/t = x/15, x = length of train.
(x/15)*10 = 100.
x = 150m.
SK Lodhi said:
1 decade ago
T = 15 Sec.
T+100 = 25 Sec.
--------------
T = 100/10 = 10 m/s where 10 sec. = 25-10(difference).
T = Length of the train
T = 15 Sec.*10 m/s=150 m.
Length of the train = 150 m.
T+100 = 25 Sec.
--------------
T = 100/10 = 10 m/s where 10 sec. = 25-10(difference).
T = Length of the train
T = 15 Sec.*10 m/s=150 m.
Length of the train = 150 m.
Keshab Karmakar said:
1 decade ago
Let trains length is X meter.
When cross the pole the train goes in 1 sec = (100 + X) /25.
When cross the platform the train goes in 1 sec = X/25.
The equation:
(100 + X) /25 = X/25.
X=150.
So the length is 150 m.
When cross the pole the train goes in 1 sec = (100 + X) /25.
When cross the platform the train goes in 1 sec = X/25.
The equation:
(100 + X) /25 = X/25.
X=150.
So the length is 150 m.
James said:
1 decade ago
Let Speed = x m/s.
Distance = 15x m = 15*10 = 150.
Time = 15 secs.
Using d = st,
15x + 100) = 25x.
x = 10.
Therefore - distance = 15x m = 15*10 = 150.
Distance = 15x m = 15*10 = 150.
Time = 15 secs.
Using d = st,
15x + 100) = 25x.
x = 10.
Therefore - distance = 15x m = 15*10 = 150.
Seema duhan said:
1 decade ago
Let train's length be x meters,
Then, train speed=train length/the time taken to cross the poll.
= x/15.
Train speed=total distance/the time to cross the platform,
x/15 = (x+100)/25.
x = 150.
Then, train speed=train length/the time taken to cross the poll.
= x/15.
Train speed=total distance/the time to cross the platform,
x/15 = (x+100)/25.
x = 150.
Neha said:
1 decade ago
Please let me know if we can take time as 25-15=10sec.
And solve it as,
Speed=100/10=10sec.
So D/T=S
It means x+100/25=10
x+100=10*25
x=250-100
x=150m.
And solve it as,
Speed=100/10=10sec.
So D/T=S
It means x+100/25=10
x+100=10*25
x=250-100
x=150m.
Madhavi said:
1 decade ago
Thank you pavan.
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