Aptitude - Problems on Trains - Discussion

Relative speed can be used only when the jogger covers 240 m in the said time. But he already is 240 m ahead of the train. Jogger is also moving, so he might also cover some distance, we have to calculate his distance. And we have to add that distance x +240 m + 120 meter. We have no idea about this distance x right?

The relative speed is 10m/s. But train needs to cover 240+2*(length of train) to pass the jogger so the answer should be 48 m/s.

@Ishan.

You explained very clearly! thank you.

I think the platfr0m length n0 need t0 take. The train thake 8 sec t0 pass the man. After concider the relative speed.

120/ (36*5/18).

This question asks "In how much time will the train pass the jogger".

Here, this rule is wrongly applied in the explanation: "Distance to be covered" = 240 + 120 m (i.e. "train length" and the distance between "jogger and engine".).

As Per the question, the "Distance to be covered" should be 120 m (i.e Train length).

It doesn't make sense why this explanation is wrongly taking into consideration 240m i.e. "Distance between Train engine and Jogger"?

@All.

Hi, I think the question is incorrect because if they are going in the same direction then train already ahead and has high speed than jogger so the train will go away.

Distance= speed * time.
120+240=45-9km/h*time,
360=36km/h*time,
360=36*5/18*time,
360=2*5*time,
360=10*time,
Time=360/10,
Time=36s.

What about the extra distance Jogger has travelled in those 36 seconds?

Why we are considering full length of the platform as 240m?

It is very much possible that the train will cross the jogger before the platform (240m) is fully covered.

Then why total distance= 120m+240m?

Here the equation is (l1+l2)/(v2+v1).