Answer:
Therefore the initial amount of animal was 89.
Step-by-step explanation:
Given that,at rate of 3.5% per year, the population of a certain animal species decreases.
The population growth formula:
[tex]A=P(1+r)^n[/tex]
A= number of population after n year.
P= initial population.
n= time in year
r= rate of growth per annum.
Here A=80, P=?, n= 3 years, r= -3.5% = -0.035[ since the rate of growth decrease]
Putting the all values,
[tex]80=P(1-0.035)^3[/tex]
[tex]\Rightarrow 80= P(0.965)^3[/tex]
[tex]\Rightarrow P=\frac{80}{(0.965)^3}[/tex]
   ≈89.
Therefore the amount of animal at its initial stage was 89.
