A country's population in 1990 was 59 million. In 2002 it was 63 million. Estimate the population in 2018 using exponential growth formula. Round your answer to the nearest million

The formula for exponential growth is P = Ae^kt

P = new population

A = starting population

k is a constant

and t is number of years.

e is a logarithm function

using the 2 known years

we know 2002-1990 = 12 years

the population in 2002 was 63 million, population in 1990 was 59 million

so using the above equation we can solve for k:

63 = 59e^k12

divide both sides by 59:

63/59 = e^k12

1.06779 = e^k12

find logorithm of left side to get rid of the e on the right side:

ln 1.06779 = k12

0.06559 = k12

divide both sides by 12 for k:

k = 0.06559 / 12 = 0.00546644

now we want to find population in 2018

2018 - 1990 = 28 years

so now t = 28 using the same formula we have:

P = 59e^ (0.00546644*28)

P = 68.758 million

rounded to nearest million = 69 million people