Suppose a countrys population in 1980 is 210 million. In 1990 it was 225 million using the A = 210 million if t=0 in 1980 find the value of t in 1990

P=Ae^kt

225 = 210 * e^ (k * (1990-1980)

225/210=e^10k

ln (225/210) = 10k

k=ln (225/210) / 10=0.0069

P = 210*e^ (0.0069t) for 2000 = = = > t = 2000-1980=20

P = 210*e^ (0.0069*20)

P=241.0749=241