A long and straight row of soldiers is marching with constant speed. The dog of the commander runs along the row from the end till the beginning, from the beginning till the end, from the end till the beginning etc. This takes always 2 minutes, 1 minute, 2 minutes, etc.
At some point the soldiers have to pass a very small bridge. However, the commander does not trust the strength bridge completely. He wonders how much time it will take them to pass the bridge when they stay marching with the same speed. How much time is that?

The last will of a horse breeder is that all his horses are to be given to his three children in the following ratio: 1/2:1/3:1/9. At the moment the horse breeder passed away he owned 17 horses. How could his last will be followed?

What is the mean distance between two randomly choosen points within a sphere of radius 1?