Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 22)
22.
Two goods train each 500 m long, are running in opposite directions on parallel tracks. Their speeds are 45 km/hr and 30 km/hr respectively. Find the time taken by the slower train to pass the driver of the faster one.
12 sec
24 sec
48 sec
60 sec
Answer: Option
Explanation:

Relative speed = = (45 + 30) km/hr
= ( 75 x 5 ( m/sec
18
= ( 125 ( m/sec.
6

We have to find the time taken by the slower train to pass the DRIVER of the faster train and not the complete train.

So, distance covered = Length of the slower train.

Therefore, Distance covered = 500 m.

Therefore Required time = ( 500 x 6 ( = 24 sec.
125

Discussion:
81 comments Page 3 of 9.

Mubarak said:   7 years ago
@Kineg.

Distance covered = length of the slower train.

So, it is 500m.

Kineg said:   7 years ago
Can anyone explain to me how the distance came 500?

B Kapil said:   7 years ago
The right answer will be 24 sec because here it is talking about the time to pass the driver, so the answer will be 24 sec, not 48sec.

Paul said:   7 years ago
This sum is followed by : t= (a+b)/(u+v).

Where: a is the length of the first train.
b: length of other trains.
u and v are the respective velocity.

Shubham said:   7 years ago
The correct answer is 48 sec.

Shree said:   7 years ago
Thanks for explaining the answer.

Sarang said:   7 years ago
Distance =speed * time,
500=45+30km/h*time,
500=75*5/18*time,
500=75*.277*time,
500=20.7*time,
Time=500/20.7=24s.

Ganda said:   8 years ago
Here answer should be 48 explain it with given example let the speed of the first train be 4m/s and second be 1m/s and length of trains be 5/5 m then you should make number line and get two seconds so we must add 5+5 10m and divides by 5m/ (1+4).

Nanda Kishor said:   8 years ago
@Raju.

In this problem, the relative speed is 75km/hr.
And to find the answer we have to convert the speed into m/s. So(75*5/18= 125/6m/s).
Hope that this will help you.

Raju said:   8 years ago
How 125÷6 came in this problem? Please explain.


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