Psychologists believe that when a person is asked to recall a set of facts, the number of facts recalled after t minutes is given by a function of the form Q(t) = A(1 − e^−kt), where k is a positive constant and A is the total number of relevant facts in the person’s memory.

a. Sketch the graph of Q(t).

b. What happens to the graph as t increases without bound? Explain this behavior in practical terms.