## Algebra 2 (1st Edition)

If for an exponential function $y=ab^x$ $a\gt0,b\gt1$, then it is an exponential growth function and $b$ is the growth factor. $a$ is the initial amount, and the percent increase is $b-1$. Hence here the initial amount is $0.42$, the percent increase is $2.47-1=1.47$, and the growth factor is $2.47$.