Answer
$B'(2000)$ is the rate of change of the number of US $\$$20 bills in circulation in the year 2000.
$B'(2000) = 0.156$
Work Step by Step
$B'(2000)$ is the rate of change of the number of US $\$$20 bills in circulation in the year 2000.
We can estimate the value of $B'(2000)$:
$B'(2000) = \frac{5.77-4.21}{2005-1995} = 0.156$
In the year 2000, the number of US $\$$20 bills in circulation was increasing at a rate of $0.156$ billion bills per year.