সঠিক উত্তর হচ্ছে: 6 seconds
ব্যাখ্যা: Length of the 1st train = 105 m
Length of the 2nd train = 90 m
Relative speed of the trains,
= 45 + 72 = 117 kmph
= (117×5)/18
= 32.5 m/sec
Time taken to cross each other,
= (Length of 1sttrain + length of 2nd train) / relative speed of the trains
∴ Time taken = 195/32.5
= 6 secs.