If it's a geometric sequence then:
[tex]a_1=27;\ a_2=27\\\\r=\dfrac{a_2}{a_1}\to r=\dfrac{27}{36}=\dfrac{3}{4}=0.75\\\\a_{n+1}=a_nr\\\\a_3=27\cdot0.75=20.25\ CORRECT[/tex]
We calculate the fourth and fifth term of the sequence:
[tex]a_4=a_3r\to a_4=20.25\cdot0.75=15.1875\\\\a_5=a_4r\to a_5=15.1875\cdot0.75=11.390625[/tex]
Answer:
In year 4 15.1875 animals.
In year 5 11.390625 animals.
