Given:
it is given that the current population of a threatened animal species is 1.3 million, but it is declining with a half-life of 25 years.
Find:
we have to find that how many animals will be left in 35 years and in 80 years.
Explanation:
we know 1.3million = 1300000
The decay law is
[tex]P(t)=1300000\times(\frac{1}{2})^{\frac{t}{25}}[/tex]
where t is in years and p(t) is the population at time t.
Now, the number of animals left in 35 years is
[tex]\begin{gathered} P(35)=1300000\times(\frac{1}{2})^{\frac{35}{25}} \\ P(35)=1300000\times(\frac{1}{2})^{1.4} \\ P(35)=492608(by\text{ rounded to nearest whole number\rparen} \end{gathered}[/tex]Therefore, 492608 animals will be left in 30 years.
Now, the number of elements left in 80 years is
[tex]\begin{gathered} P(80)=1300000\times(\frac{1}{2})^{\frac{80}{25}} \\ P(80)=1300000\times(\frac{1}{2})^{3.2} \\ P(80)=141464(by\text{ rounded to nearest whole number\rparen} \end{gathered}[/tex]