Calculate total distance travelled by bee | Puzzles for Interview - Interview Preparation PDF Download

Introduction

This puzzle involves two trains on the same track coming towards each other. The first train moves at a speed of 50 km/h while the second train moves at a speed of 70 km/h. A bee starts flying between the trains when the distance between them is 100 km. The bee flies back and forth between the trains until they collide. The puzzle requires us to calculate the total distance travelled by the bee.

Solution

To solve this puzzle, we need to use the formula: Distance = Speed × Time. Let the first train A move at a speed of u km/h, while the second train B moves at a speed of v km/h. Let the distance between the two trains be d km, and let the speed of the bee be b km/h. Therefore, the time taken by the trains to collide is given by t = d/(u+v).

Putting in the values
We know that u = 50 km/h, v = 70 km/h, d = 100 km, and b = 80 km/h. Substituting these values in the above equation, we get t = 100/(50+70) = 1 hour.
Now, since the bee flies back and forth between the trains until they collide, it covers a distance equal to the distance between the two trains, which is 100 km, every time the trains pass each other. Therefore, the total distance travelled by the bee is given by Distance = Speed × Time = b × t = 80 × 1 = 80 km.

Conclusion

Thus, the total distance travelled by the bee is 80 km.