Answer:
-0.04 = decrease of 4%
Step-by-step explanation:
[tex]\boxed{\begin{minipage}{6.3 cm}\underline{Average rate of change of function $f(x)$}\\\\$\dfrac{f(b)-f(a)}{b-a}$\\\\over the interval $a \leq x \leq b$\\\end{minipage}}[/tex]
Given interval:
Therefore:
Given values:
Substitute the values into the formula:
[tex]\begin{aligned}\textsf{Average rate of change}&=\dfrac{f(1940)-f(1920)}{1940-1920}\\\\&=\dfrac{45.3-46.1}{1940-1920}\\\\&=\dfrac{-0.8}{20}\\\\&=-0.04\end{aligned}[/tex]
Therefore, the average rate of change was -0.04 which is a decrease of 4%.