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.
Srinu said:
10 years ago
If a train crosses 300 metres long platform in 38 seconds while it crosses a signal pole in 18 seconds. What is the speed of the train in km/h?
Arjun said:
6 years ago
Let x be the length of train.
Therefore speed of train = x/15 m/sec.
x+100 = (x/15) m/sec * 25 sec.
3x+300 = 5x.
x = 300/2 =150 m.
Therefore speed of train = x/15 m/sec.
x+100 = (x/15) m/sec * 25 sec.
3x+300 = 5x.
x = 300/2 =150 m.
Dhiru said:
9 years ago
Speed of train = length of platform/difference of time.
= 100/(25 - 15) = 10km/h.
Then distance=speed * time.
= 10 * 15 = 150 m.
= 100/(25 - 15) = 10km/h.
Then distance=speed * time.
= 10 * 15 = 150 m.
Kiranjit Misra said:
1 decade ago
Let speed = X; then length of train = 15 X;
Hence (15X+100)/X = 25.
Answer the length of train is 15X = 10*15 = 150.
Hence (15X+100)/X = 25.
Answer the length of train is 15X = 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.
SANTOSH said:
8 years ago
Can we calculate the speed of the train by the length of platform and time taken by train to cross the platform?
Nayana said:
1 decade ago
Hi,.
Can any one explain me why they have taken 15 sec for calculating speed of train but not 25 sec?
Can any one explain me why they have taken 15 sec for calculating speed of train but not 25 sec?
Shubham lad said:
3 years ago
Can we calculate the speed of the train 100/25=4 m/s and length = 15 * 4 = 60m?
Please explain.
Please explain.
(5)
Sangita said:
8 years ago
Why x multiply with 100 and exactly which formula is used here? Please, clearly explain this.
JIJINA said:
1 decade ago
100+L/25=SPEED
L/15=SPEED
(100+SPEED*15)=25*SPEED
100=10SPEED
SPEED=10
LENGTH L= 150.
L/15=SPEED
(100+SPEED*15)=25*SPEED
100=10SPEED
SPEED=10
LENGTH L= 150.
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