Aptitude - Problems on Trains - Discussion

Discussion Forum : Problems on Trains - General Questions (Q.No. 14)
14.
Two trains 140 m and 160 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time (in seconds) which they take to cross each other, is:
9
9.6
10
10.8
Answer: Option
Explanation:

Relative speed = (60 + 40) km/hr = 100 x 5 m/sec = 250 m/sec.
18 9

Distance covered in crossing each other = (140 + 160) m = 300 m.

Required time = 300 x 9 sec = 54 sec = 10.8 sec.
250 5

Discussion:
42 comments Page 1 of 5.

Akhil v said:   2 weeks ago
Thanks all for explaining the answer.

Indraneel Mal said:   2 years ago
72kmph = 20m/sec.
In 26 seconds, the distance covered = 20 * 26 = 520m.
As the length of the platform is 250m.
Therefore the length of the train = 520 - 250 = 270m.
(5)

Syed abbas said:   2 years ago
How is it possible 9/250 and 54/5?
(2)

Sourabh Sonwane said:   5 years ago
a = 140
b = 160
u = 60km/h
v = 40km/h
u+v = 60 + 40 = 100km/h.

Now convert km/h into m/s then,
100*5/18=27.77.
As we know the formula.
a+b/u + v.
Putting all values in formulas.
140 + 160/27.77 = 10.8.
(6)

Sabikun said:   5 years ago
54/5 = 1.8.
How it could be 10.8.

Aishi sasmal said:   6 years ago
@Deep.

t = dis/speed.
300/250/9 = 300*9/250.
(1)

Deep said:   6 years ago
Why we calculate 9/250 instead of 250/9?
(2)

Javeed khan said:   6 years ago
(100*5%8).
27.7m/s,
140+260 = 300,
300/27.7 =10.8.
(1)

Yash said:   7 years ago
How it will come 10.8?

Please Explain me.
(1)

Deepak said:   7 years ago
How it will come 10.8?

Please Explain me.
(1)


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