Chapter 5 - Exponential Functions - 5.5 Exponential Growth and Decay Rates and Compounding Interest - 5.5 Exercises - Page 469: 10

$99.9\%$ decay.

Growth or decay rate $r=b-1$ where $r$ is a percentage written as a decimal and $b$ is the base of an exponential function of the form $g(x)=a\cdot b^{x}$. Given $g(x)=5000(0.001)^{x}$ $\implies b=0.001$ $r=b-1=0.001-1=-0.999$ Or $r=-0.999\times100 \%=-99.9\% $ $r$ is negative. So, there is $99.9\%$ decay.