Question

a country's population in 1992 was 72 million. In 1996 was 76 million.Estimate the population in 2012 using the exponational growth formula. Round your answer to the nearest million.

Answer 1

Let  S1-----------starting population
       Sn ----------final population

Sn = S1 * exp(k * t)

Where k is a constant that we can find.

From 1992 to 1996 there are four years (t = 4)

Sn = 76 million
S1 = 72 million

Sn/S1 = exp(k*4) = 1.055..............> ln(1.055) = k*4

k = ln(1.055)/4 = 0.0135

Now, from 1996 (our new starting point) to 2012, there are 16 years

so,  t =16, k = 0.0135, S1 = 76 million

Sn = 76million * exp (0.0135*16) = 94.323 million............> 94 million