Two trains of equal length, running in opposite directions, pass a pole in 18 and 12 seconds. The trains will cross each other in?Options20.2 seconds15.5 seconds14.4 seconds18.8 seconds

To solve this problem, we first need to find the speed of each train.

1. Speed is calculated by the formula Speed = Distance/Time. Here, the distance is the length of the train. Since the trains are of equal length, we can say the length of the train is the same as the distance each train travels to pass the pole.

2. For the first train, it takes 18 seconds to pass the pole. So, the speed of the first train is Distance/18.

3. For the second train, it takes 12 seconds to pass the pole. So, the speed of the second train is Distance/12.

4. When two objects are moving in opposite directions, their relative speed is the sum of their individual speeds. So, the relative speed of the two trains is (Distance/18) + (Distance/12).

5. To find the time it takes for the two trains to cross each other, we use the formula Time = Distance/Speed. Here, the distance is the sum of the lengths of the two trains (which is 2*Distance because the trains are of equal length) and the speed is the relative speed we calculated.

6. Substituting the values in, we get Time = 2*Distance / [(Distance/18) + (Distance/12)].

7. Simplifying this, we get Time = 2 / [(1/