Nit: I think that should be 1-(1-.0.27)^25 ~= 0.5. Obviously it ends up being about 1/2 either way, but you're measuring the chance that you used one of the nod

Nit: I think that should be 1-(1-.0.27)^25 ~= 0.5. Obviously it ends up being about 1/2 either way, but you're measuring the chance that you used one of the nodes, not that you avoided all of them.