A country's population in 1994 was 195 million. In 2002 it was 199 million. How do you estimate the population in 2016 using the exponential growth formula?

1 Answer
Mar 7, 2016

Population in 2016 is estimated to be 206.20 million

Explanation:

Let the population in starting year be P_0 and g be the exponential growth. Then the population P_n in n^th will be given by P_n=P_0xx(1+g)^n.

As the population in 1994 was 195 million and in 2002 (after 8 years), it was 199 million. We have

199=195xx(1+g)^8 or (1+g)^8=199/195.

Taking log, 8xxlog(1+g)=log199-log195=0.0088185 or

log(1+g)=0.0011022 or 1+g=1.002541 or g=0.002541 i.e.

Growth rate is 0.2541%.

The population in 2016 (after 22 years) would be

195xx(1+g)^22 or 195xx1.002541^22=195xx1.0574279=206.20 million.