Consider a truncated icosahedron with 12 pentagons and 20 hexagons. Starting from a hexagonal face, we go to any neighboring polygon randomly with equal probability. What is the expected number of steps it takes for us to visit the starting hexagon a second time?
I know that this is easily solvable with a Markov Chain, but the question specifically requires little computation, stating that the problem can be finished with just simple mental math. I know the answer to be 30, but I cannot find an elegant way to assert so.
One argument is that since 3/2 is the expected number of steps from one hexagon to another, and there are 20 hexagons, that the answer is simply 3/2 times 20, which is 30. However, this clearly lacks rigor.