Question 549234
Train T1 is 72 metres long
and is travelling at  (108km/h. 
T2 is 78 metres long and is travelling  (72km/h). 

T1 & T2 are travelling in opposite directions
so add up speed = 108+72=180 km/h

Distance = sum of lengths of trains (72+78)=150 m= 0.15km

time = d/r
t=0.15/180
t=0.00083 hours

1 hour = 3600 seconds
0.000833*3600= 3 seconds

Time to pass= 3 seconds

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