Answer
a. $f(x)=0.1375x^2 + 0.7x + 37.8$
b. $x\gt52\ mph$
Work Step by Step
a. The quadratic regression for the wet pavement data is shown in the figure and we get the function as
$f(x)=0.1375x^2 + 0.7x + 37.8$
b. Letting $f(x)\gt446$, we have $0.1375x^2 + 0.7x + 37.8\gt446$ or $0.1375x^2 + 0.7x -408.2\gt0$, which can be solved graphically as shown in the figure with solutions of $x\gt52\ mph$
