Respuesta :
Given:
Consider the given function is:
[tex]P(t)=4000(1.2)^t[/tex]
To find:
a. The type of exponential function (growth or decay).
b. Percentage change in population.
c. Population after 5 years.
Solution:
a. The general exponential function is:
[tex]P(t)=P_0(1+r)^t[/tex] ...(i)
Where, [tex]P_0[/tex] is the initial population and r is the rate of change in decimal.
If r<0, then the function represents exponential decay and if r>0, then the function represents exponential growth.
We have,
[tex]P(t)=4000(1.2)^t[/tex]
It can be written as:
[tex]P(t)=4000(1+0.2)^t[/tex] ...(ii)
On comparing (i) and (ii), we get
[tex]P_0=4000[/tex]
[tex]r=0.2[/tex]
Since r>0, therefore the given function represents exponential growth.
b. From part (a), we have
[tex]r=0.2[/tex]
So, the rate of change in the population is 0.2. Multiply is by 100 to get the percentage change in population.
[tex]r\%=0.2\times 100[/tex]
[tex]r\%=20\%[/tex]
Therefore, the yearly percentage change in population is 20%.
c. We have,
[tex]P(t)=4000(1.2)^t[/tex]
Substitute [tex]t=5[/tex] in the given function to find the population living on the island after 5 years.
[tex]P(5)=4000(1.2)^5[/tex]
[tex]P(5)=4000(2.48832)[/tex]
[tex]P(5)=9953.28[/tex]
[tex]P(5)\approx 9953[/tex]
Therefore, the estimated population living on the island after 5 years is 9953.
