An has the form $y=ab_{x},$ where $a =0$ and the base $b$ is a positive real number other than $1.$ Let's determine and interpret $a$ and $b$ of the given model.
$y=2500(1.50)_{t} $
In this situation, $a$ represents the number of subscribers it received at the beginning of the model. Because $b$ is greater than $0$ and less than $1,$ it represents the growth factor of the number of referrals each year. To determine the annual percent increase, we should consider the
$y=a(1+r)_{t} $
In the model, $r$ is the percent increase written as a decimal and the quantity $1+r$ is the growth factor. Knowing that the growth factor is $1.50$ in our situation, we can find the percent increase.
$1−r=1.50⇒r=0.50orr=50% $