Exponential Function Solution Equation - Decay (Discrete) Scenario to Rate

Question

Rearrange the exponential equation to solve for  for the rate given this scenario?

A whale population starts at 300. Each subsequent year it declines by a certain percent. After 8 years it has decreased to a population of 216 whales.

Accepted Answer

$$r = -(\frac{216}{300})^{ \frac{1}{8} } - 1$$

Answer

$$r = -(\frac{216}{300})^{ \frac{8}{2} } - 1$$

Answer

$$r = +(\frac{216}{300})^{ \frac{1}{8} } + 1$$