Answer:
The growth rate is of 0.085 = 8.5% a year.
Step-by-step explanation:
General growth equation:
[tex]B(t) = B(0)(1+r)^{t}[/tex]
In which B(t) is the population of butterflies after t years, B(0) is the initial population and r is the growth rate, as a decimal.
We have:
[tex]B(t)=137(1.085)^{t}[/tex]
Comparing to the general equation, we have that:
[tex]B(0) = 137, 1 + r = 1.085[/tex]
Growh rate:
1 + r = 1.085
r = 1.085 - 1
r = 0.085
The growth rate is of 0.085 = 8.5% a year.