In a linear birth and death process with birth rate= death rate a >0, assume that there are only two events (an event is a death or a birth) occurred in time interval [0, 2t]. One occurred at time t and the other occurred at time 2t. (a) What is the expected population size at time 2t, if the initial population size is n=2? (Express your answer in terms of a) (b) Find this answer as a goes to 0.