Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 16)
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 10 of 13.

Srj said:   8 years ago
Do we want to change miles to meters?

Milson marcelin said:   8 years ago
No because both are in miles.

Sunny Singla said:   8 years ago
Aas per my understanding it's 3.2.

Total distance cover by train in minutes : 75/60 = 1.25,
Total Distance need to cover : 3.5+.25(enter)+.25(exit) = 4 miles,
In one minute it cover : 1.25 m.
Minutes required to travel 4 miles = 4/1.25 = 3.2.

Chaitu said:   8 years ago
Y isn't miles converted to kms?

Sathish said:   8 years ago
Distance/speed = time.

So.

15/4 * 75 means it comes (15/4) /75 so 15*75/4 is the way is correct why 15/4*75? Explain.

Varsha said:   8 years ago
How 15/4*75 hrs?

Ashu said:   8 years ago
We must add two times the distance of the train because we are just calculating the time needed to cross the tunnel if we just add one time the length of the train. So the answer must be 3.2min.

It doesn't need to explain the question that if we add only one time.

Tushar V. Ladukar said:   8 years ago
In the question as length of the tunnel is mentioned 3 miles and length of train 1 miles, how 7/2 and 1/4 is taken respectively?

S.D.Brite said:   8 years ago
@Ashu.

They ask only for the time to cross the tunnel...
The train is driven by the engine, which is in the front part of the train.
;So we need to calculate the distance as;
7/2 mile + 1/4 mile = 3.75 mile.

~Banu said:   7 years ago
Why put 7/2 In total distance covered?


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