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 P=Ae^(kt)P=Aekt?

1 Answer
May 28, 2017

207207 million

Explanation:

For this problem, we have the final population PP, the starting population AA, and the time passed tt.

We still need to determine the value of the growth factor kk.

This can be done using the information for the years 19941994 and 20022002.

In this case, AA will be 195195 million (the population in 19941994), PP will be 199199 million (the population in 20022002), and tt will be 88 years (the number of years between 19941994 and 20022002):

Rightarrow P = A e^(k t)P=Aekt

Rightarrow 199 = 195 e^(k times 8)199=195ek×8

Rightarrow frac(199)(195) = e^(8 k)199195=e8k

Applying lnln to both sides of the equation:

Rightarrow ln(frac(199)(195)) = ln(e^( 8k))ln(199195)=ln(e8k)

Using the laws of logarithms:

Rightarrow 8 k ln(e) = ln(199) - ln(195)8kln(e)=ln(199)ln(195)

Rightarrow 8 k = ln(199) - ln(195)8k=ln(199)ln(195)

Rightarrow k = frac(ln(199) - ln(195))(8)k=ln(199)ln(195)8

therefore k = 0.00253815825

Now, let's use this information to determine P in 2016.

A will still be 195 million, but t will be 22 years.

Rightarrow P = 195 e^(0.00253815825 times 22)

Rightarrow P = 195 e^(0.0558394815)

Rightarrow P = 195 times 1.057427933

therefore P = 206.19844694

Therefore, the population in 2016 will be around 207 million.