The Ladder Problem

I like to solve physics problems. Here is one for you (I just made it up).

A 4 meter ladder leans against a frictionless wall at a 30 degree angle. The mass of the ladder is 10 kg. A human stands 1 meter up the ladder and has a mass of 70 kg. What is the minimum coefficient of static friction between the floor and the ladder so that the ladder doesn’t slip?

Here is the solution-in video form.