Aptitude - Problems on Trains - Discussion

To me, answer is 41 if the pole and the platform consider separately.

650-240=410.

Now it crosses 240m in 24s.
So, 410m in 41s.
If both pole and platform consider jointly the answer will be 89s. I understood 2nd case. But my Mind also with the 1st case. I think the question is ambiguous. Or am I wrong?

Yes, you are right @Kumar.

Pole is given to just calculate the speed of the train, In the question, nowhere mention pole is on the platform so the answer is 65 m/s.

Since the train has to cross the platform, it is not on the platform. It has to completely cross the platform means it crosses it's length.

Therefore total distance becomes train's length+ platform's length =890m.

Time = 890/10 = 89sec.

89 sec is the correct answer.

Here pole consider as a point of reference, but platform not a point if consider engine only cross the platform from starting of platform to end (i.e also consider as crossed) 65 sec is correct, but if consider entire train (engine to the last van) cross the platform end to end length of the platform should be added hence 89sec is correct.

Why we are adding the time of poles with the time of platforms?

Length of train(distance)=240m
Time=24sec
Formula: length(distance)=speed x time
240=speed x 24
speed=240/24
speed=10sec.

Now it has to pass platform of 650m
The total length of platform =650m
train length = 240m
The total distance the train pass the platform = 650+240=890m.
Because as the train entered the platform(650m) the train remaining part was outside the platform (240m).
So total distance the train cover is 890.

Why did you add 240?

Distance= speed * time,
240/ 24=time,
Time = 10s,
Distance= speed* time.
240+ 650 combing distance = 890,
890/10= time,
89 m/s.