Answer
(a) $23.2\ million$
(b) $2020$
(c) They are close.
(d) $17.5\ million$
(e) see explanations.
Work Step by Step
(a) Given $y=0.3143x+21.95$, for year 2018, we have $x=2018-2014=4$ and $y=0.3143(4)+21.95=23.2\ million$
(b) Let $y=24$, we have $24=0.3143x+21.95$ which gives $x\approx6$ corresponding to year $2020$
(c) From the graph, we can read the number as $23.2$ for 2018 (which is the same as in (a)), and $23.9$ for 2020 (which is close to 24 as in (b))
(d) For year 2000, we have $x=2000-2014=-14$, use the model $y=0.3143(-14)+21.95\approx17.5\ million$
(e) There is a big difference between the predicted number and the real number, it means that it is better to use this model in the given year range.
