Answer
a) $83.33$
b)$105$
Work Step by Step
a) The average rate is given as: $\dfrac{f(b)-f(a)}{b-a}$ where $a \leq b$
$\dfrac{f(1890)-f(1860)}{1890-1860}=\dfrac{4500-2000}{30}=83.33$
b) Apply the rule such as
The average rate is given as: $\dfrac{f(b)-f(a)}{b-a}$ where $a \leq b$
$\dfrac{f(1970)-f(1950)}{1970-1950}=\dfrac{4900-2800}{20}=105$
