9. A virus is found to exist in N different strains and in each generation either stays the same or mutates into another strain with probability p/ (N 1). Show that the probability that the strain in the nth generation is the same as that at time zero is 1+111 ION\" N N Ni' [Hint: Model this as a 2-state Markov process with the two states being \"initial strain" and \"other strain\".]