Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - Data Sufficiency 3 (Q.No. 1)
Directions to Solve

Each of these questions is followed by three statements. You have to study the question and all the three statements given to decide whether any information provided in the statement(s) is redundant and can be dispensed with while answering the given question.


At what time will the train reach city X from city Y?


The train crosses another train of equal length of 200 metres and running in opposite directions in 15 seconds.


The train leaves city Y at 7.15 a.m. for city X situated at a distance of 558 km.


The 200 metres long train crosses a signal pole in 10 seconds.

I only
II only
III only
II and III only
All I, II and III are required.
Answer: Option

From the statement I, we get length of the train is 200 metres (Redundant info while comparing with Statement III). The rest of the info given in this statement cannot be used for calculating the speed of the train, because the two trains might run at different speed.

III gives, speed = 200 m/sec = 20 m/sec = 20 x 18 km/hr = 72 km/hr.
10 5

II gives, time taken = 558 hrs = 31 hrs = 7 3 hrs = 7 hrs 45 min.
72 4 4

So, the train will reach city X at 3 p.m.

Hence II and III only gives the answer.

30 comments Page 1 of 3.

Sneha said:   6 months ago
Why 558km divided with 72?

Can anyone explain this?

Khushi said:   4 years ago
The question wasn't framed correctly, but I think they asked us to find the statements which are important to find the solution while dispensing the statement which is redundant. So, the correct answer is D.

Mandal said:   4 years ago
Yes, A is the answer as A is redundant.

Basil said:   5 years ago
Here, It was to identify the redundant criteria. How it was II and III only? Please explain in detail.

Vianny said:   5 years ago
Can anyone explain 558/72?

Somya gupta said:   6 years ago
How 3pm? I can't understand anyone explain.

Kittu said:   6 years ago
Redundant means unnecessary. That means which one is unnecessary. Then how option d is the answer?

Shubham said:   7 years ago
Question is to identify the redundant statement, so the answer should be 1 right?

Shubham said:   7 years ago
18/5 is simply multiplied to convert m/s into km/hr.

1m/s = (1m/1000)km/(1s/60 * 60)hr,
= (1/1000)km/(1/3600)hr,
= 3600/1000,
= (18/5) km/hr.

It is the factor of converting 1m/s. So it has been multiplied directly.

Amar said:   7 years ago
Can you please explain 20*18/5 how did you got 18/5?

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