Tengo aquí un problemon de carácter matemático.

Pero mi primer problemon es: No sé cómo decirlo enteramente

en español. Así que, voy a hacerlo en Inglés, if I may.


Two trains were heading toward each other on a collision course along the same

tracks (rieles). One was travelling at a constant speed of 75 mph (miles per hour),

the other at 85 mph.

At the same time, a fly was travelling continously back and forth between the two

on-coming trains, at a constant speed of 80 mph.

Then, at the end of two hours, the two trains finally collided head-on, thereby

crushing the fly between them.


What is the total distance travelled by the fly before it was crushed between

the two trains?

ojo: Este problemon no es tan dificil como os parezca.

Just think it out very carefully.

Thanx y saludos.


Si la mosca voló a 80 km/h dirante dos horas. Recorrió 160 km.
But the insect was flying back and forth

between the two approaching trains !

I don't think the direction the fly was flying along has much to do here, it was moving at constant speed (80 km/h) during two hours.

e = v * t = 80 km/h * 2 h = 160 km
I had to ask you that follow-up question. I was hoping that you would clarify the irrelevance of the direction of flight in a simple, easy to understand manner without using any "arithmetic". [H]

So, to put your answer in simple terms: "If one drives his car at the constant speed of 80 mph, at the end of 2 hours he will have covered a total distance of 160 miles. It doesn't matter whether he drives back and forth, zig-zagging or in one straight line. The total distance covered in 2 hours will be the same."

Gracias. 'ta luego.