Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 25)
25.
A train 108 m long moving at a speed of 50 km/hr crosses a train 112 m long coming from opposite direction in 6 seconds. The speed of the second train is:
Answer: Option
Explanation:
Let the speed of the second train be x km/hr.
| Relative speed | = (x + 50) km/hr | |||||||
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![]](/_files/images/aptitude/1-sym-cbracket-h1.gif)
Distance covered = (108 + 112) = 220 m.
 |
220 | = 6 | ||
|
250 + 5x = 660
x = 82 km/hr.
Discussion:
77 comments Page 3 of 8.
Srinivas8126 said:
1 decade ago
Hi Sundar.
What you said is right we have taken x in terms on km/hr, considering above explanation while converting relative speed we use (x + 50) km/hr both speeds converted into meters/seconds in next step. So final answer will be in m/s how it will be in km/hr?.
What you said is right we have taken x in terms on km/hr, considering above explanation while converting relative speed we use (x + 50) km/hr both speeds converted into meters/seconds in next step. So final answer will be in m/s how it will be in km/hr?.
Arun said:
10 years ago
Relative speed = x+50 km/hr.
6 = 220/(x+50)*(5/18).
5/3 = 220/(x+50).
x+50 = 132.
x = 82 m/sec.
Please explain, how km/hr.
And one more method.
6/3600= (220*10^-3)/(x+50).
x+50 = 600*0.22.
x = 142-50.
x = 92 km/hr.
Now I am totally confused. Please help.
6 = 220/(x+50)*(5/18).
5/3 = 220/(x+50).
x+50 = 132.
x = 82 m/sec.
Please explain, how km/hr.
And one more method.
6/3600= (220*10^-3)/(x+50).
x+50 = 600*0.22.
x = 142-50.
x = 92 km/hr.
Now I am totally confused. Please help.
(1)
Harisha said:
1 decade ago
Here the ans is in km/hr. so frm starting onwards we sould calculate
the problem without converting into m/s.
Let speed of d second train= xkm/hr
Distance covered=(108+112)=220m=0.22km
Time=6sec= 6/3600hr =1/600hr
So
1/600hr= 0.22km/(50+x)
x=82km/hr
the problem without converting into m/s.
Let speed of d second train= xkm/hr
Distance covered=(108+112)=220m=0.22km
Time=6sec= 6/3600hr =1/600hr
So
1/600hr= 0.22km/(50+x)
x=82km/hr
Rutika said:
10 years ago
S = D/T.
So, D = 108+112 = 220 m.
= 220/1000 km/hr.
T = 6 sec = 6/3600 = 1/600 hr.
S = 50 km/hr.
We assume second train speed 'x'.
Relative speed = 50 km/hr+x km/hr.
S = D/T.
= 50+x = 220/1000*600.
= 50+x = 22*6 = 50+x = 132.
x = 82 km/hr.
So, D = 108+112 = 220 m.
= 220/1000 km/hr.
T = 6 sec = 6/3600 = 1/600 hr.
S = 50 km/hr.
We assume second train speed 'x'.
Relative speed = 50 km/hr+x km/hr.
S = D/T.
= 50+x = 220/1000*600.
= 50+x = 22*6 = 50+x = 132.
x = 82 km/hr.
Rajata said:
1 decade ago
Total distance = 108+112 = 220 m.
Time = 6s.
Relative speed = distance/time = 220/6 m/s = 110/3 m/s.
= (110/3)x(18/5) km/hr = 132 km/hr.
=> 50 + speed of second train = 132 km/hr.
=> Speed of second train = 132-50 = 82 km/hr.
Time = 6s.
Relative speed = distance/time = 220/6 m/s = 110/3 m/s.
= (110/3)x(18/5) km/hr = 132 km/hr.
=> 50 + speed of second train = 132 km/hr.
=> Speed of second train = 132-50 = 82 km/hr.
Priyanka said:
9 years ago
Total distance = 112 + 120 = 220 m.
Time = 6 sec.
Relative speed = total distance / time,
=> 220/6 m/s
Speed in km/h,
=> 220/6 * 18/5 = 132.
Speed of second train = relative speed - speed of 1st train,
=> 132- 50 = 82 km/h.
Time = 6 sec.
Relative speed = total distance / time,
=> 220/6 m/s
Speed in km/h,
=> 220/6 * 18/5 = 132.
Speed of second train = relative speed - speed of 1st train,
=> 132- 50 = 82 km/h.
Sundar said:
1 decade ago
Hi Raj,
Please note that
At the first step we are taking the speed of the second train be x KM/HR.
At final step we are finding the value of 'x'.
So, the answer is 'x' km/hr.
Thats why the answer is in km/hr.
Please note that
At the first step we are taking the speed of the second train be x KM/HR.
At final step we are finding the value of 'x'.
So, the answer is 'x' km/hr.
Thats why the answer is in km/hr.
(1)
Sagar said:
4 years ago
@All.
First, we are assumed as X in km/hr, but we are applying the formula convert into M/S it is applicable for RELATIVE SPEED=(X+50).
It is not applicable for Assuming X, so the final answer is in KM/H.
First, we are assumed as X in km/hr, but we are applying the formula convert into M/S it is applicable for RELATIVE SPEED=(X+50).
It is not applicable for Assuming X, so the final answer is in KM/H.
(5)
Roji said:
1 decade ago
Hey shyam sharma if I do in your method what you said the problem formula not getting answer yar.
t = 220/ (v+50)*(5/18).
t = 6.
v = 82 got directly.
And hence no need 2 convert again 2 m/sec why?
t = 220/ (v+50)*(5/18).
t = 6.
v = 82 got directly.
And hence no need 2 convert again 2 m/sec why?
Darshan Kumar said:
1 decade ago
@Karthika , see when we take the series 220/5x+250/18=6 than the 18 will go up side and new series came 220*18/5x+250=6 , so here the formula 18/5 km/h is applicable .
I think ur doubt is clear
I think ur doubt is clear
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