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Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 16)
Problems on Trains
16.
A train travelling at a speed of 75 mph enters a tunnel 31/2 miles long. The train is 1/4 mile long. How long does it take for the train to pass through the tunnel from the moment the front enters to the moment the rear emerges?
2.5 min
3 min
3.2 min
3.5 min
Answer: Option
Explanation:

Total distance covered
= ( 7 + 1 ( miles
2 4
= 15 miles.
4

Therefore Time taken
= ( 15 ( hrs
4 x 75
= 1 hrs
20
= ( 1 x 60 ( min.
20
= 3 min.

Discussion:
129 comments Page 12 of 13.
Phaneendra said:   7 years ago
I think here 75 is kmph not mph.
Praveen said:   7 years ago
So, if I change the speed to 90mph, then according to the way this is solved, the time would increase. Now that does not sound right to me. Can anyone explain this, please ?
Kumar tamang said:   7 years ago
How come 15/4 could you explain?
Naresh said:   7 years ago
Total distance covered.
= 7/2 + 1/4.
=15/4 miles.

Can anyone explain me, how to convert it?
Siddhant said:   7 years ago
@All.

Assume that there's a platform of length 7/2 miles and train of length 1/4 miles.
So now we just have to calculate the time taken by train to pass the platform.
Hence total distance = 15/4 miles.

No need to add 1/4 twice.

Hope you will understand.
Ajit said:   7 years ago
Because 75mph that means 75 miles per hour, not metres.
Mani Prasath said:   7 years ago
How it's comes 15/4?

Please explain.
Satya said:   6 years ago
Yeah, We have to convert the mile to km.
Akshay Agrawal said:   6 years ago
15/4.

(7/2 +1/4) = let take hcm of this i.e. 4.
Then, (7*2/4 +1/4),
(14+1/4)=15/4.
Mahedi bipul said:   6 years ago
mph means mile per hour or metres per hour?

Which one is correct?
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