Ratio of length of two trains is 5 : 7. Coming from opposite direction, they cross a pole in 5 seconds each . Then in what time will they cross each other .
Answer & explanation
Correct answer: option 4
Ratio of train 1 : train 2
Distance 5 : 7
Speed 5 : 7 ( distance = speed × time , so ratio of distance and speed is same .)
As both train cross a man in 5 sec . So length of train1
Distance = Speed × Time
Length of train 1 = 5R × 5 = 25R
Similarly, legth of train 2 = 7R × 5 = 35R
Total distance = 60R meter
As trains moves in opposite direction . so relative speed = ( 7 + 5 )R = 12R m/sec
Time taken by trains to cross each other = \(\frac{60R}{12R}\) = 5 sec .