George used this formula because he has not given the period or the rate or number. Therefore, by using this formula all he needs to find out is the just the model.
A= the final value you end up with
A = the initial value you start with
T= 8-1, because that was the time of the initial and final count.
Model= is the unknown or what George is trying to find out.
The formula is used to find out both the bacteria and white blood cell model. George could check if hes answer is correct by substituting the model in. The answer on the right should be very close to the answer on the left side.
