Based on the census data, the population of whoville was 43,230 in the year of 2000 and has been growing at a rate of 3.5%

Awrite an expontional modle for the population P(t), where t represents the number of years since 2000.
Busing your model, what is the estimated population in 2015?

Verified Answer :

The model would take the form of

\(P(t)=P(0)e^{0.035t}\)

So in 2015, when \(t=15\), the population would be

\(P(15)=43230e^{0.035\times15}\approx73079\)

On the other hand, you could use the following discrete model for the population, which gives a similar result. If \(t=0\) corresponds to the year 2000, then in 2001, when \(t=1\), you have

\(P(1)=P(0)\times1.035^1\approx44743\)

In the next year,

\(P(2)=P(1)\times1.035^1=P(0)\times1.035^2\approx46309\)

And so on, making the general pattern for the \(t\)th year to be

\(P(t)=P(t-1)\times1.035^1=P(t-2)\times1.035^2=\cdots=P(0)\times1.035^t\)

This means in the year 2015, or when \(t=15\), the population should be approximately

\(P(15)=P(0)\times1.035^{15}\approx72425\)