Bee Puzzle Solution.

This puzzle is little confusing and on hearing for the first time people gets confused as to what is asked in the question.

Lets look at the puzzle.

Length of the tunnel = 200 km
Speed of train 1 = 100 km/h
Speed of train 2 = 100 km/h
Speed of Bee = 1000 km/h

So Relative velocity of both the trains as both are moving in opposite directions.
100+100 = 200 km/h.
So the time taken by the trains before the collision happened is 200/200 = 1 hour

So the bee will travel for 1 hour before the collision.
Speed of bee = 1000 km/h
so distance traveled by the bee will be 1000*1 = 1000 km before the collision would take place.