Using an exponential function, it is found that at the beginning, there were 328 hornets.
An increasing exponential function has the following format:
[tex]A(t) = A(0)(1 + r)^t[/tex]
In which:
In this problem, there is a growth of 20%, hence [tex]r = 0.2[/tex].
After 5 months, the size is of 815, hence, when [tex]t = 5, A(t) = 815[/tex], and this is used to find A(0).
[tex]A(t) = A(0)(1 + r)^t[/tex]
[tex]815 = A(0)(1 + 0.2)^5[/tex]
[tex]A(0) = \frac{815}{(1.2)^5}[/tex]
[tex]A(0) = 328[/tex]
At the beginning, there were 328 hornets.
A similar problem is given at https://brainly.com/question/22733028