Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 13)
13.
Two trains, each 100 m long, moving in opposite directions, cross each other in 8 seconds. If one is moving twice as fast the other, then the speed of the faster train is:
Answer: Option
Explanation:
Let the speed of the slower train be x m/sec.
Then, speed of the faster train = 2x m/sec.
Relative speed = (x + 2x) m/sec = 3x m/sec.
 |
(100 + 100) | = 3x |
| 8 |
24x = 200
| x = |
25 | . |
| 3 |
| So, speed of the faster train = | 50 | m/sec |
| 3 |
| = |  |
50 | x | 18 |  km/hr |
| 3 | 5 |
= 60 km/hr.
Discussion:
74 comments Page 5 of 8.
Vaibhav said:
1 decade ago
Here there is no need of finding relative speed right? then why we find relative speed?
Divya said:
1 decade ago
Here there is no need of finding relative speed right? then why we find relative speed?
Sudha said:
1 decade ago
When you divide 200/24, you won't get 25/3? So I request you to explain me properly.
(1)
Dewansh said:
6 years ago
Why the relative speed is the sum of individual speeds rather than the difference?
Sunil bhanovath said:
7 years ago
@Nutan.
Why 50/3 taken as speed of the train is 2x so that's why we should take.
Why 50/3 taken as speed of the train is 2x so that's why we should take.
RAHAMAN said:
1 decade ago
SOLVING WITHOUT x
{(100+100)/8}*{(18/5)}=90K/H
NOW,
SPEED=2:1
SO,
90*2/3=60K/H
{(100+100)/8}*{(18/5)}=90K/H
NOW,
SPEED=2:1
SO,
90*2/3=60K/H
Sudha said:
1 decade ago
I did not understand how you got 50/3? Please I need a clear explanation.
Manivel said:
6 years ago
@Punam.
Substitute the X value in faster train 2X, 2* (25/3) =50/3. M.
Substitute the X value in faster train 2X, 2* (25/3) =50/3. M.
Innie said:
4 years ago
If x= 25/3, how is 2x= 50/3?
It should have been 50/6. Am I right?
It should have been 50/6. Am I right?
(2)
Jagdish said:
2 decades ago
I don't understand how is speed of the faster train = 50/3 m/sec.
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