Answer
(a) $y=412x+6312$
(b) $7960\ dollars$, underestimate 110 dollars.
Work Step by Step
(a) Identify the data points as $(0,6312),(2, 7136)$, we can fine the equation as $y-6312=\frac{7136-6312}{2-0}(x)$ or $y=412x+6312$
(b) For year 2013, we have $x=4$ and $y=412(4)+6312=7960\ dollars$ which underestimates the actual number (8070) by 110 dollars.
