One Infected Hermit

Each circle represents a hermit. Each red circle represents a hermit who gets the disease. Blue lines are drawn as one hermit visits another.

It is impossible for only one hermit to be infected, because the problem states that the first infected hermit "randomly visits one of the other hermits during his infectious period."
Hermit #3 randomly gets the disease.He randomly visits another hermit, who cannot be immune yet.
Hermit #5 is randomly visited and, because he is not immune, he gets the disease.

Return to the analytical solution.

Or continue to the explanation page for 2 infected hermits.