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 1 of 6.
Gowtham said:
2 decades ago
Please explain the question in detail.
MOHANRAJ.A said:
2 decades ago
Assume that length is x meters.
Speed y m/sec, speed=distance/time
so, y=x/15.------------------------1.
Like the same calculate after crossing the platform
y=x+100/25--------------------2
LHS equal. So
x+100/25=x/15;
15(x+100)=25x
Then remaing sme as above.
Speed y m/sec, speed=distance/time
so, y=x/15.------------------------1.
Like the same calculate after crossing the platform
y=x+100/25--------------------2
LHS equal. So
x+100/25=x/15;
15(x+100)=25x
Then remaing sme as above.
Prabhakaran said:
2 decades ago
I can't understand step 2 mohanraj can you explain again clearly.
Pavan said:
2 decades ago
Why we take x/y=15 can you please explain me?
Priya said:
2 decades ago
@pavan
Since we have declared x-distance,y-speed
According to the below given formula,
Time=Distance/speed
Here Train speed time is specified as 15 sec so,
15 =x/y
Since we have declared x-distance,y-speed
According to the below given formula,
Time=Distance/speed
Here Train speed time is specified as 15 sec so,
15 =x/y
Rajesh said:
2 decades ago
other way is select any option and solve for both case
Jelli said:
2 decades ago
i think i will try explain simple
1.s=d/t=x(length or distance covered by train)/15
s=x/15
2.the same train to cross cross 100m long platform is
s=d/t
x/15(it's by step1) =(100+x)/25
then we can get x=150m
thank u
1.s=d/t=x(length or distance covered by train)/15
s=x/15
2.the same train to cross cross 100m long platform is
s=d/t
x/15(it's by step1) =(100+x)/25
then we can get x=150m
thank u
Santhanalakshmi. said:
2 decades ago
sorry for late reply..to pbn..
in train pblms length=distance..
in step 2 the length of thetrain is added with the length of the platform tat it s crossin..X+100(100 is length of the platform)
than asusual.speed=dis/tim=100+x/25
25 is the time aftrcrossing the platform.. it think u got.
in train pblms length=distance..
in step 2 the length of thetrain is added with the length of the platform tat it s crossin..X+100(100 is length of the platform)
than asusual.speed=dis/tim=100+x/25
25 is the time aftrcrossing the platform.. it think u got.
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?
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.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers