Answer
(a) $108.1\ million$
(b) $2004$
Work Step by Step
(a) Given $y=0.2313x^2+2.600x+35.17$. for year 2007, we have $x=2007-1994=13$, thus $y=0.2313(13)^2+2.600(13)+35.17\approx108.1\ million$
(b) Let $y=90$, we have $90=0.2313x^2+2.600x+35.17$ or $0.2313x^2+2.600x-54.83=0$ which can be solved using the quadratic formula (discard the negative answer) to get $x\approx8$ meaning year $1994+8=2004$
