Your exponential growth formula, P(t) = A e^(kt), contains two unknown constants, A and k. Once you find them, you can find the population for any t. (I assume, t is measured in years.) From your "story", you have:
<span>72 million = P(1992) = A e^(1992 k) </span> <span>76 million = P(1998) = A e^(1998 k) </span>
<span>From these two equations, you can find the two unknowns A and k (do it yourself). Once you do, your answer is </span>