calculate the distance

There is a 50m long army platoon marching ahead. The last person in the platoonwants to give a letter to the first person leading the platoon. So while the platoon ismarching he runs ahead, reaches the first person and hands over the letter to him andwithout stopping he runs and comes back to his original position.In the mean time the whole platoon has moved ahead by 50m.The question is how much distance did the last person cover in that time. Assuming that  

he ran the whole distance with uniform speed.

Solution is   http://good-interview-puzzles.blogspot.com/2011/09/solution-for-calculating-distance-it-is.html