there are two trains moving towards each other with a constant velocity "v" . When the trains are a distance "D" appart a bird sitting on the engine of the 1st train starts to fly towards the second train that is coming from the front. The birds velocity is "B" that is B>v.
The bird touches the 2 nd trains and immidiately turns back to wards the first and keeps on doing this till both trains collide.
What is distance traveled by the bird
Hint : sum of infinite series...
Is each train moving at "v" or are there approaching each other at "v" (e.g., each train moving at v/2)?
Remark to hint: you can solve this using sum of infinite series if you want to. But why, when you can solve this in your head without it?
Former Senior Instructor, Manhattan GMAT and VeritasPrep
Vice President, Midtown NYC Investment Bank, Structured Finance IT
MFE, Haas School of Business, UC Berkeley, Class of 2005
MBA, Anderson School of Management, UCLA, Class of 1993