Top Puzzle 6: The Two Trains Puzzle | Puzzles for Interview - Interview Preparation PDF Download

Have you ever heard of the puzzle of two trains and a flying bird? It's a classic problem that challenges your math skills and logic. Let's break it down into parts.

Premise

In this puzzle, there are two trains at points A and B respectively, with a distance of 120km between them. A bird is sitting on top of the train at point A.

Rule

When the trains start moving towards each other at a constant speed of 60 km/hr, the bird also starts flying toward the other train, at a speed of 200km/hr. When it reaches the train, it turns back and flies towards the first train and repeats the step over and over till both the trains collide.

The Objective

The main question is, how much distance does the bird cover during the whole journey?

Solution

To solve this puzzle, we need to understand the speed and distance of the trains. The speed of Train A is 60km/hr, and the speed of Train B is also 60km/hr. Since both trains are moving towards each other, their relative speed will be the sum of their individual speeds, which is 120km/hr.
Using the formula of distance = speed x time, we can calculate the time in which the trains will collide with each other. The distance between the trains is 120km, and their relative speed is 120km/hr. Therefore, the time taken by the trains to collide with each other is 1 hour.
Now, we can calculate the distance covered by the bird during this time. As the bird flies at a speed of 200km/hr, it covers a distance of 200km in one hour. However, the bird does not fly continuously for one hour, as it turns back and forth between the trains. Therefore, we need to calculate the time for which the bird flies towards each train.
As the distance between the trains is 120km, the bird flies 60km towards Train B in half an hour (since it travels at a speed of 200km/hr). Similarly, it flies another 60km towards Train A in the next half-hour. This cycle continues till the trains collide.
Therefore, the bird covers a distance of 120km (60km towards each train) during the one hour in which the trains collide.

Conclusion

The puzzle of two trains and a flying bird may seem complicated, but with a little bit of math and logic, we can solve it easily. So, if you ever come across such puzzles, don't be afraid to take them on!