Two trains 130 m and 170 m in length are running towards each other on parallel tracks, one at the rate of 50 km/hr and at 70 km/hr respectively. In how many seconds will they cross each-other?
15 sec
6 sec
9 sec
12 sec
Solution
Required time $= \dfrac{(130 + 170) \times 18}{(50 + 70) \times 5}$
$= \dfrac{300 \times 18}{120 \times 5} = 9$ seconds