Question

a country's population in 1994 was 76 million. In 1998 it was 81 millio. estimate the population in 2016 using the exponential growth formula

Answer 1

81 - 76 = 5. So it grew 5 million in 4 years.
5,000,000 / 4 = 1250000
1250000 * 18 = 22500000

Answer 2

The exponential relation is given by,
\[Y = Yo * a^{n}\]
Where,
Y is the Population at 2016
Yo is the Population at 1994
a is the Growth rate of the population
n is the number of years from the starting year to the final year

For the above problem
n = 12 and Yo = 76000000
Y and a are unknown...

To find 'a' use the given data:
By substituting the given data for population at 1998, in the exponential relation we get,
\[81000000 = 76000000 * a ^{4}\]
By solving the above equation you get the value of 'a',

With this 'a' using the exponential relation you can find the population at 2016